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Mathematics · Class 11 Science

Ch 9Differential Calculus – Limits and Continuity — Class 11 Mathematics, concept-first.

Calculus is fundamentally the mathematics of change, and its reach extends across virtually every branch of science and social science. Whenever an observer wants to know not just the value of a changing quantity but how fast it is changing — the rate of change — calculus is the tool required, because most changing qua…

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9.1

Introduction

Calculus is fundamentally the mathematics of change, and its reach extends across virtually every branch of science and social science.

9.2

Limits

This section develops the notion of a limit carefully, moving from an intuitive, table-and-graph based understanding towards a small set of theorems that let limits be computed mechanically rather tha…

9.2.1

The calculation of limits

The idea of a limit asks a very specific question: as the input of a function is pushed closer and closer to some fixed value (without ever actually landing on ), what value does the output get closer…

9.2.2

One sided limits

Several of the illustrations in the previous section relied informally on the idea of approaching a point from just one side; this section makes that idea precise.

+Exercise 9.1i23 questions
  1. Q1Complete the table using a calculator and use the result to estimate the limit. $$\lim_{x\to2}\dfrac{x-2}{x^2-x-2}$$ | $x$ | $1.9$ | $1.99$…Free
  2. Q2Complete the table using a calculator and use the result to estimate the limit. $$\lim_{x\to2}\dfrac{x-2}{x^2-4}$$ | $x$ | $1.9$ | $1.99$ |…Free
  3. Q3Complete the table using a calculator and use the result to estimate the limit. $$\lim_{x\to0}\dfrac{\sqrt{x+3}-\sqrt3}{x}$$ | $x$ | $-0.1$…Free
  4. Q4Complete the table using a calculator and use the result to estimate the limit. $$\lim_{x\to-3}\dfrac{\sqrt{1-x}-2}{x+3}$$ | $x$ | $-3.1$ |…Preview
  5. Q5Complete the table using a calculator and use the result to estimate the limit. $$\lim_{x\to0}\dfrac{\sin x}{x}$$ | $x$ | $-0.1$ | $-0.01$ |…Preview
  6. Q6Complete the table using a calculator and use the result to estimate the limit. $$\lim_{x\to0}\dfrac{\cos x-1}{x}$$ | $x$ | $-0.1$ | $-0.01$…Preview
  7. Q7Use the graph (Fig. 9.13) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to3}(4-x)$$ ![Graph of the st…Preview
  8. Q8Use the graph (Fig. 9.14) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to1}(x^2+2)$$ ![Graph of the…Preview
  9. Q9Use the graph (Fig. 9.15) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to2}f(x),\qquad \text{where }…Preview
  10. Q10Use the graph (Fig. 9.16) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to1}f(x),\qquad \text{where }…Preview
  11. Q11Use the graph (Fig. 9.17) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to3}\dfrac1{x-3}$$ ![Graph of…Preview
  12. Q12Use the graph (Fig. 9.18) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to5}\dfrac{|x-5|}{x-5}$$ ![Gr…Preview
  13. Q13Use the graph (Fig. 9.19) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to1}\sin(\pi x)$$ ![Graph of…Preview
  14. Q14Use the graph (Fig. 9.20) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to0}\sec x$$ ![Graph of y = s…Preview
  15. Q15Use the graph (Fig. 9.21) to find the limit, if it exists. If the limit does not exist, explain why. $$\lim_{x\to\pi/2}\tan x$$ ![Graph of y…Preview
  16. Q16Sketch the graph of $f$, then identify the values of $x_0$ for which $\displaystyle\lim_{x\to x_0}f(x)$ exists. $$f(x)=\begin{cases}x^2, & x…Preview
  17. Q17Sketch the graph of $f$, then identify the values of $x_0$ for which $\displaystyle\lim_{x\to x_0}f(x)$ exists. $$f(x)=\begin{cases}\sin x,…Preview
  18. Q18Sketch the graph of a function $f$ that satisfies the given values. **(i)** $f(0)$ is undefined $\displaystyle\lim_{x\to0}f(x)=4$ $f(2)=6$ $…Preview
  19. Q19Write a brief description of the meaning of the notation $\displaystyle\lim_{x\to8}f(x)=25$.Preview
  20. Q20If $f(2)=4$, can you conclude anything about the limit of $f(x)$ as $x$ approaches $2$?Preview
  21. Q21If the limit of $f(x)$ as $x$ approaches $2$ is $4$, can you conclude anything about $f(2)$? Explain your reasoning.Preview
  22. Q22Evaluate $\displaystyle\lim_{x\to3}\dfrac{x^2-9}{x-3}$, if it exists, by finding $f(3^-)$ and $f(3^+)$.Preview
  23. Q23Verify the existence of $\displaystyle\lim_{x\to1}f(x)$, where $$f(x)=\begin{cases}\dfrac{|x-1|}{x-1}, & x\ne1\\ 0, & x=1\end{cases}$$Preview
9.2.3

Theorems on limits

Building a table of values or sketching a graph every time a limit needs to be found is neither practical nor rigorous.

9.2.4

Infinite limits and limits at infinity

Not every limit settles down to a finite real number as approaches a point — sometimes the function values grow without any bound at all.

9.2.5

Limits at infinity

Section 9.2.4 let approach a finite point and asked what happens to when becomes unbounded. This section reverses the roles: now itself is allowed to grow without bound (positively or negatively), and…

9.2.6

Limits of rational functions

For a rational function , the technique of Section 9.2.5 (divide by the highest power of in the denominator) can be packaged into a single rule of thumb that avoids repeating the division every time,…

9.2.7

Applications of limits

Limits at infinity and one-sided limits are not merely abstract exercises — they routinely answer a natural real-world question: "what is the extreme (maximum or minimum, long-run or boundary) behavio…

9.2.8

Sandwich Theorem

Some limits cannot be evaluated by any of the algebra-of-limits theorems directly — typically because the expression involves a factor, such as , that oscillates and has no limit of its own.

9.2.9

Two special Trigonometrical limits

Result 9.1. (a) (b) .

9.2.10

Some important other limits

Result 9.2.

+Exercise 9.4i28 questions
  1. Q1Evaluate the following limit: $$\lim_{x\to\infty}\left(1+\dfrac1x\right)^{7x}$$Free
  2. Q2Evaluate the following limit: $$\lim_{x\to0}(1+x)^{1/(3x)}$$Free
  3. Q3Evaluate the following limit: $$\lim_{x\to\infty}\left(1+\dfrac kx\right)^{m/x}$$Free
  4. Q4Evaluate the following limit: $$\lim_{x\to\infty}\left(\dfrac{2x^2+3}{2x^2+5}\right)^{8x^2+3}$$Preview
  5. Q5Evaluate the following limit: $$\lim_{x\to\infty}\left(1+\dfrac3x\right)^{x+2}$$Preview
  6. Q6Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sin^3(x/2)}{x^3}$$Preview
  7. Q7Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sin\alpha x}{\sin\beta x}$$Preview
  8. Q8Evaluate the following limit: $$\lim_{x\to0}\dfrac{\tan2x}{\sin5x}$$Preview
  9. Q9Evaluate the following limit: $$\lim_{\alpha\to0}\dfrac{\sin(\alpha^n)}{(\sin\alpha)^m}$$Preview
  10. Q10Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sin(a+x)-\sin(a-x)}{x}$$Preview
  11. Q11Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sqrt{x^2+a^2}-a}{\sqrt{x^2+b^2}-b}$$Preview
  12. Q12Evaluate the following limit: $$\lim_{x\to0}\dfrac{2\arcsin x}{3x}$$Preview
  13. Q13Evaluate the following limit: $$\lim_{x\to0}\dfrac{1-\cos x}{x^2}$$Preview
  14. Q14Evaluate the following limit: $$\lim_{x\to0}\dfrac{\tan2x}{x}$$Preview
  15. Q15Evaluate the following limit: $$\lim_{x\to0}\dfrac{2^x-3^x}{x}$$Preview
  16. Q16Evaluate the following limit: $$\lim_{x\to0}\dfrac{3^x-1}{\sqrt{x+1}-1}$$Preview
  17. Q17Evaluate the following limit: $$\lim_{x\to0}\dfrac{1-\cos^2x}{x\sin2x}$$Preview
  18. Q18Evaluate the following limit: $$\lim_{x\to\infty}x\left[3^{1/x}+1-\cos\!\left(\dfrac1x\right)-e^{1/x}\right]$$Preview
  19. Q19Evaluate the following limit: $$\lim_{x\to\infty}\big\{x[\log(x+a)-\log(x)]\big\}$$Preview
  20. Q20Evaluate the following limit: $$\lim_{x\to\pi}\dfrac{\sin3x}{\sin2x}$$Preview
  21. Q21Evaluate the following limit: $$\lim_{x\to\pi/2}(1+\sin x)^{2\csc x}$$Preview
  22. Q22Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sqrt2-\sqrt{1+\cos x}}{\sin^2x}$$Preview
  23. Q23Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sqrt{1+\sin x}-\sqrt{1-\sin x}}{\tan x}$$Preview
  24. Q24Evaluate the following limit: $$\lim_{x\to\infty}\left(\dfrac{x^2-2x+1}{x^2-4x+2}\right)^{x}$$Preview
  25. Q25Evaluate the following limit: $$\lim_{x\to0}\dfrac{e^x-e^{-x}}{\sin x}$$Preview
  26. Q26Evaluate the following limit: $$\lim_{x\to0}\dfrac{e^{ax}-e^{bx}}{x}$$Preview
  27. Q27Evaluate the following limit: $$\lim_{x\to0}\dfrac{\sin x(1-\cos x)}{x^3}$$Preview
  28. Q28Evaluate the following limit: $$\lim_{x\to0}\dfrac{\tan x-\sin x}{x^3}$$Preview
9.3

Continuity

Continuity is the mathematical way of capturing an everyday intuition — that many natural processes change smoothly, without sudden jumps: a rod expanding continuously as it is heated, an organism gro…

9.3.1

Examples of functions Continuous at a point

At every point of their domain, the following standard families of functions are continuous — each fact follows directly from the algebra-of-limits theorems (Section 9.2.3) applied at a general point…

9.3.2

Algebra of continuous functions

Just as limits combine algebraically (Theorem 9.2), so does continuity — which should be unsurprising, since continuity is itself defined directly in terms of limits.

9.3.3

Removable and Jump Discontinuities

40 Q

Not all discontinuities are the same "kind" — some can be patched by simply reassigning a single function value, while others cannot be patched at all no matter what value is chosen.

+Exercise 9.5i15 questions
  1. Q1Prove that $f(x)=2x^2+3x-5$ is continuous at all points in $\mathbb R$.Free
  2. Q2Examine the continuity of the following: **(i)** $x+\sin x$ **(ii)** $x^2\cos x$ **(iii)** $e^x\tan x$ **(iv)** $e^{2x}+x^2$ **(v)** $x\ln x…Free
  3. Q3Find the points of discontinuity of the function $f$, where **(i)** $f(x)=\begin{cases}4x+5, & x\le3\\ 4x-5, & x>3\end{cases}$ **(ii)** $f(x…Free
  4. Q4At the given point $x_0$ discover whether the given function is continuous or discontinuous, citing reasons for your answer: **(i)** $x_0=1,…Preview
  5. Q5Show that the function $$f(x)=\begin{cases}\dfrac{x^3-1}{x-1}, & x\ne1\\ 3, & x=1\end{cases}$$ is continuous on $(-\infty,\infty)$.Preview
  6. Q6For what value of $\alpha$ is the function $$f(x)=\begin{cases}\dfrac{x^4-1}{x-1}, & x\ne1\\ \alpha, & x=1\end{cases}$$ continuous at $x=1$?Preview
  7. Q7Let $$f(x)=\begin{cases}0, & x<0\\ x^2, & 0\le x<2\\ 4, & x\ge2\end{cases}$$ Graph the function. Show that $f(x)$ is continuous on $(-\infty…Preview
  8. Q8If $f$ and $g$ are continuous functions with $f(3)=5$ and $\displaystyle\lim_{x\to3}[2f(x)-g(x)]=4$, find $g(3)$.Preview
  9. Q9Find the points at which $f$ is discontinuous. At which of these points is $f$ continuous from the right, from the left, or neither? Sketch…Preview
  10. Q10A function $f$ is defined as follows: $$f(x)=\begin{cases}0, & x<0\\ x, & 0\le x<1\\ -x^2+4x-2, & 1\le x<3\\ 4-x, & x\ge3\end{cases}$$ Is th…Preview
  11. Q11Which of the following functions $f$ has a removable discontinuity at $x=x_0$? If the discontinuity is removable, find a function $g$ that a…Preview
  12. Q12Find the constant $b$ that makes $g$ continuous on $(-\infty,\infty)$: $$g(x)=\begin{cases}x^2-b^2, & x<4\\ bx+20, & x\ge4\end{cases}$$Preview
  13. Q13Consider the function $f(x)=x\sin\dfrac\pi x$. What value must we give $f(0)$ in order to make the function continuous everywhere?Preview
  14. Q14The function $f(x)=\dfrac{x^2-1}{x^3-1}$ is not defined at $x=1$. What value must we give $f(1)$ in order to make $f(x)$ continuous at $x=1$…Preview
  15. Q15State how continuity is destroyed at $x=x_0$ for each of the following graphs (Fig. 9.38-9.41). **(a)** A curve drawn for $x<x_0$ ends at a…Preview
+Exercise 9.6i25 questions
  1. Q1$\displaystyle\lim_{x\to\infty}\dfrac{\sin x}{x}$ (1) $1$ (2) $0$ (3) $\infty$ (4) $-\infty$Free
  2. Q2$\displaystyle\lim_{x\to\pi/2}\dfrac{2x-\pi}{\cos x}$ (1) $2$ (2) $1$ (3) $-2$ (4) $0$Free
  3. Q3$\displaystyle\lim_{x\to0}\dfrac{\sqrt{1-\cos2x}}{x}$ (1) $0$ (2) $1$ (3) $\sqrt2$ (4) $\text{does not exist}$Free
  4. Q4$\displaystyle\lim_{\theta\to0}\dfrac{\sin\sqrt\theta}{\sqrt{\sin\theta}}$ (1) $1$ (2) $-1$ (3) $0$ (4) $2$Preview
  5. Q5$\displaystyle\lim_{x\to\infty}\left(\dfrac{x^2+5x+3}{x^2+x+3}\right)^{x}$ is (1) $e^4$ (2) $e^2$ (3) $e^3$ (4) $1$Preview
  6. Q6$\displaystyle\lim_{x\to\infty}\dfrac{\sqrt{x^2-1}}{2x+1}=$ (1) $1$ (2) $0$ (3) $-1$ (4) $\dfrac12$Preview
  7. Q7$\displaystyle\lim_{x\to\infty}\dfrac{a^x-b^x}{x}=$ (1) $\log ab$ (2) $\log\!\left(\dfrac ab\right)$ (3) $\log\!\left(\dfrac ba\right)$ (4)…Preview
  8. Q8$\displaystyle\lim_{x\to0}\dfrac{8^x-4^x-2^x+1}{x^2}=$ (1) $2\log2$ (2) $2(\log2)^2$ (3) $\log2$ (4) $3\log2$Preview
  9. Q9If $f(x)=x(-1)^{\left\lfloor\frac1x\right\rfloor},\ x\le0$, then the value of $\displaystyle\lim_{x\to0}f(x)$ is equal to (1) $-1$ (2) $0$ (…Preview
  10. Q10$\displaystyle\lim_{x\to3}\lfloor x\rfloor=$ (1) $2$ (2) $3$ (3) $\text{does not exist}$ (4) $0$Preview
  11. Q11Let the function $f$ be defined by $f(x)=\begin{cases}3x, & 0\le x\le1\\ -3x+5, & 1<x\le2\end{cases}$, then (1) $$\displaystyle\lim_{x\to1}f…Preview
  12. Q12If $f:\mathbb R\to\mathbb R$ is defined by $f(x)=\lfloor x-3\rfloor+|x-4|$ for $x\in\mathbb R$, then $\displaystyle\lim_{x\to3^-}f(x)$ is eq…Preview
  13. Q13$\displaystyle\lim_{x\to0}\dfrac{xe^x-\sin x}{x}$ is (1) $1$ (2) $2$ (3) $3$ (4) $0$Preview
  14. Q14If $\displaystyle\lim_{x\to0}\dfrac{\sin px}{\tan3x}=4$, then the value of $p$ is (1) $6$ (2) $9$ (3) $12$ (4) $4$Preview
  15. Q15$\displaystyle\lim_{\alpha\to\pi/4}\dfrac{\sin\alpha-\cos\alpha}{\alpha-\pi/4}$ is (1) $\sqrt2$ (2) $\dfrac1{\sqrt2}$ (3) $1$ (4) $2$Preview
  16. Q16$\displaystyle\lim_{n\to\infty}\left(\dfrac1{n^2}+\dfrac2{n^2}+\dfrac3{n^2}+\cdots+\dfrac n{n^2}\right)$ is (1) $\dfrac12$ (2) $0$ (3) $1$ (…Preview
  17. Q17$\displaystyle\lim_{x\to0}\dfrac{e^{\sin x}-1}{x}=$ (1) $1$ (2) $e$ (3) $\dfrac1e$ (4) $0$Preview
  18. Q18$\displaystyle\lim_{x\to0}\dfrac{e^{\tan x}-e^x}{\tan x-x}=$ (1) $1$ (2) $e$ (3) $\dfrac12$ (4) $0$Preview
  19. Q19The value of $\displaystyle\lim_{x\to0}\dfrac{\sin x}{\sqrt{x^2}}$ is (1) $1$ (2) $-1$ (3) $0$ (4) $\infty$Preview
  20. Q20The value of $\displaystyle\lim_{x\to k^-}\big(x-\lfloor x\rfloor\big)$, where $k$ is an integer, is (1) $-1$ (2) $1$ (3) $0$ (4) $2$Preview
  21. Q21At $x=\dfrac32$ the function $f(x)=\dfrac{|2x-3|}{2x-3}$ is (1) $\text{continuous}$ (2) $\text{discontinuous}$ (3) $\text{differentiable}$ (…Preview
  22. Q22Let $f:\mathbb R\to\mathbb R$ be defined by $f(x)=\begin{cases}x, & x\text{ is irrational}\\ 1-x, & x\text{ is rational}\end{cases}$, then $…Preview
  23. Q23The function $f(x)=\begin{cases}\dfrac{x^2-1}{x^3+1}, & x\ne-1\\ P, & x=-1\end{cases}$ is not defined for $x=-1$. The value of $f(-1)$ so th…Preview
  24. Q24Let $f$ be a continuous function on $[2,5]$. If $f$ takes only rational values for all $x$ and $f(3)=12$, then $f(4.5)$ is equal to (1) $\df…Preview
  25. Q25Let a function $f$ be defined by $f(x)=\dfrac{x-|x|}{x}$ for $x\ne0$ and $f(0)=2$. Then $f$ is (1) $\text{continuous nowhere}$ (2) $\text{co…Preview
9.4

Summary

This chapter built the idea of a limit from the ground up and used it to define continuity.

Sample & Board Papers

Sample papers and previous-year board questions for this subject.

+Show 28 questions28 questions
  1. Q1The function $f(x) = \tan x$ is continuous in: (a) $\left[\dfrac{-\pi}{2}, \dfrac{\pi}{2}\right]$ (b) $(-\infty, \infty)$ (c) $\left(\dfrac{…Preview
  2. Q2$\displaystyle\lim_{x\to 0^-} \dfrac{3x+|x|}{6x+|x|}$ is: (a) $1$ (b) $\dfrac{1}{2}$ (c) $\dfrac{2}{5}$ (d) $\dfrac{5}{2}$Preview
  3. Q3Verify the continuity at the point $x=0$ for the function $f(x) = \begin{cases} \dfrac{\sin 3x}{x} + 1, & x \ne 0 \\ 2, & x = 0 \end{cases}$…Preview
  4. Q4For the function $f(x)=\begin{cases}x+2, & x>0\\ x-2, & x<0\end{cases}$ (a) $\lim\limits_{x\to 2^-} f(x)=-1$ (b) $\lim\limits_{x\to 0} f(x)$…Preview
  5. Q5Define a continuous function on the closed interval $[a, b]$.Preview
  6. Q6Consider the function $f(x)=\sqrt{x}, x\ge 0$. Does $\lim\limits_{x\to 0} f(x)$ exist?Preview
  7. Q7Examine the continuity of the function $\cot x+\tan x$.Preview
  8. Q8$\displaystyle\lim_{\theta \to 0} \dfrac{\sin\sqrt{\theta}}{\sqrt{\sin\theta}}$: (a) 1 (b) -1 (c) 0 (d) 2Preview
  9. Q9Let $f: \mathbf{R} \to \mathbf{R}$ be defined by $f(x) = \begin{cases} x, & x \text{ is irrational} \\ 1-x, & x \text{ is rational} \end{cas…Preview
  10. Q10Evaluate: $\displaystyle\lim_{x \to 1} \dfrac{(x + x^2 + x^3 + \ldots + x^n) - n}{x - 1}$Preview
  11. Q11Do the limits of following functions exist as $x \to 0$? State reasons for your answer. $\dfrac{\sin(x - \lfloor x \rfloor)}{x - \lfloor x \…Preview
  12. Q12(a) Prove that: $\displaystyle\lim_{\theta \to 0} \dfrac{\sin\theta}{\theta} = 1$ **OR** (b) If $x = a(\theta + \sin\theta)$, $y = a(1-\cos\…Preview
  13. Q13At $x = \frac{3}{2}$ the function $f(x) = \frac{|2x-3|}{2x-3}$ is: (a) differentiable (b) continuous (c) non-zero (d) discontinuousPreview
  14. Q14$\lim_{x\to\infty} \left(\dfrac{x^2+5x+3}{x^2+x+3}\right)^x$ is: (a) $e^3$ (b) $e^4$ (c) $1$ (d) $e^2$Preview
  15. Q15$\displaystyle\lim_{x\to 0} \frac{\sqrt{1-\cos 2x}}{x} =$ (a) 1 (b) $\sqrt{2}$ (c) 0 (d) None of the abovePreview
  16. Q16Evaluate the limit $\displaystyle\lim_{\sqrt{x}\to 3} \frac{x^2-81}{\sqrt{x}-3}$.Preview
  17. Q17Evaluate: $\displaystyle\lim_{n\to\infty}\left[6^n + 5^n\right]^{\frac{1}{n}}$.Preview
  18. Q18Find the constant $b$ that makes $g$ continuous on $(-\infty,\infty)$: $g(x) = \begin{cases}x^2-b^2 & \text{if } x<4\\ bx+20 & \text{if } x\…Preview
  19. Q19$\displaystyle\lim_{x\to\infty}\dfrac{\sin x}{x}$ (a) $\infty$ (b) $1$ (c) $-\infty$ (d) $0$Preview
  20. Q20$\displaystyle\lim_{x\to 0}\dfrac{a^x-b^x}{x}=$ (a) $\log\left(\dfrac{b}{a}\right)$ (b) $\log ab$ (c) $\dfrac{a}{b}$ (d) $\log\left(\dfrac{a…Preview
  21. Q21Calculate: $\displaystyle\lim_{x\to 3}\dfrac{x^2-6x+5}{x^3-8x+7}$Preview
  22. Q22$\displaystyle\lim_{x\to 3} \lfloor x \rfloor =$ (a) Value does not exist (b) $2$ (c) $0$ (d) $3$Preview
  23. Q23Find the positive integer 'n' so that $\displaystyle\lim_{x\to 2} \dfrac{x^n - 2^n}{x - 2} = 12$Preview
  24. Q24(a) Prove that $\displaystyle\lim_{\theta\to 0} \dfrac{\sin\theta}{\theta} = 1$ **OR** (b) A factory has two Machines - I and II. Machine -…Preview
  25. Q25$f(x)=\dfrac{1}{x}$ is continuous at: (a) $(-\infty, 0]$ (b) $\mathbb{R}$ (c) $[0, \infty)$ (d) $\mathbb{R}-\{0\}$Preview
  26. Q26Prove that $f(x)=2x^2+3x-5$ is continuous at all points in $\mathbb{R}$.Preview
  27. Q27Calculate $\lim\limits_{x\to 1} \dfrac{x^{11}-1}{x-1}$Preview
  28. Q28Show that: $\displaystyle\lim_{x\to 0^+} x\left[\left\lfloor\dfrac{1}{x}\right\rfloor+\left\lfloor\dfrac{2}{x}\right\rfloor+\ldots+\left\lfl…Preview