Q.limx→2(x2−4x−2)=
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Algebra of Limits
Once the limits of two functions f and g at a point a are known — say f(x) tends to l and g(x) tends to m as x tends to a — the algebra of limits lets a complicated limit be broken apart into the limits of its simpler pieces rather than evaluated from scratch. The sum or difference of the functions tends to l plus or minus m; the product tends to l times m; a constant multiple k times f(x) tends to kl; and the quotient f(x)/g(x) tends to l/m, provided the denominator's limit m is not zero. Standing building blocks that follow from these rules include: the limit of a constant is itself, the limit of x is a, the limit of x to a natural-number power n is a^n, and for any polynomial p(x), the limit as x tends to a is simply p(a) — …
Factor x2−4=(x−2)(x+2) and cancel the common factor before substituting. …
limx→2x2−4x−2=41.
Direct substitution gives 00, an indeterminate form, so factor the denominator:
x2−4=(x−2)(x+2).
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Showing the 12 most recent of 13 on this concept.
- CBSE 2025Set ANNUAL1 markMCQQ.limx→2(x2−4x−2)=(a) 0(b) 4(c) 1/4(d) none of these
›Reveal solutionSolution
limx→2x2−4x−2=41.
Direct substitution gives 00, an indeterminate form, so factor the denominator:
x2−4=(x−2)(x+2).
…
- CBSE 2025Set ANNUAL1 markMCQQ.limθ→0cos2θ=(a) 1(b) -1(c) 0(d) 2
›Reveal solutionSolution
limθ→0cos2θ=1.
cos2θ is continuous everywhere, so by direct substitution: …
- CBSE 2025Set ANNUAL1 markMCQQ.The value of x→4limx−24x+3 will be:(a) 219(b) 2−19(c) 192(d) 19−2
›Reveal solutionSolution
Since the denominator x−2 does not vanish at x=4, the limit is evaluated by direct substitution, giving 219.
We need x→4limx−24x+3.
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- CBSE 2025Set ANNUAL1 markQ.Fill in the blank: The value of x→0limx⋅secx is ____.
›Reveal solutionSolution
Since secx is continuous and finite at x=0 (equal to 1), the limit of the product xsecx equals 0×1=0.
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- CBSE 2024Set ANNUAL1 markMCQQ.x→2limx2−5x+6x3−2x2=(a) 4(b) -4(c) 0(d) None of these
›Reveal solutionSolution
Both numerator and denominator vanish at x=2 (a 0/0 form), so factor out the common (x−2) term and cancel before substituting.
Numerator: x3−2x2=x2(x−2)
Denominator: x2−5x+6=(x−2)(x−3) (since −2 and −3 multiply to 6 and add to −5).
So:
x2−5x+6x3−2x2=(x−2)(x−3)x2(x−2)=x−3x2(xe2)
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- CBSE 2023Set ANNUAL1 markMCQQ.x→2limx2−5x+6x3−2x2=(a) 4(b) 0(c) −4(d) 2
›Reveal solutionSolution
Both numerator and denominator share a factor (x−2); cancelling and substituting x=2 gives −4.
Factor numerator and denominator:
x3−2x2=x2(x−2)
x2−5x+6=(x−2)(x−3)
So the expression simplifies (for x=2) to:
(x−2)(x−3)x2(x−2)=x−3x2
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- CBSE 2022Set TERM11 markMCQQ.x→2limx−2x2+x−6=(a) 5(b) −5(c) 00(d) 21
›Reveal solutionSolution
Factor the quadratic numerator to cancel the common factor with the denominator.
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- CBSE 2022Set ANNUAL1 markMCQQ.Lim(x→1) f(x) where f(x) = { x² - 1, x ≤ 1 ; -x² - 1, x > 1 } is:(a) 0(b) -2(c) -1(d) Does not exist
›Reveal solutionSolution
The left-hand limit is 0 and the right-hand limit is −2; since they differ, the limit does not exist.
f(x)={x2−1,−x2−1,x≤1x>1
Left-hand limit (using x2−1 since x≤1 applies as x→1−):
limx→1−f(x)=12−1=0
Right-hand limit (using −x2−1 since x>1 applies as x→1+): …
- CBSE 2020Set ANNUAL1 markMCQQ.x→2limx2−43x2−x−10=?(a) 0(b) 41(c) 411(d) none of these
›Reveal solutionSolution
Both numerator and denominator vanish at x=2 (a 00 form); factor out the common (x−2) term and cancel before substituting.
x→2limx2−43x2−x−10
Factor the numerator: 3x2−x−10=(x−2)(3x+5) (check: (x−2)(3x+5)=3x2+5x−6x−10=3x2−x−10 ✓)
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- CBSE 2019Set ANNUAL1 markMCQQ.The value of lim(x→2) (x^3 - 2x^2) / (x^2 - 5x + 6) is:(a) 0(b) 4(c) -4(d) None of these
›Reveal solutionSolution
Factor both numerator and denominator, cancel the common factor (x−2), then substitute x=2.
Numerator: x3−2x2=x2(x−2).
Denominator: x2−5x+6=(x−2)(x−3).
(x−2)(x−3)x2(x−2)=x−3x2 for x=2.
…
- CBSE 2019Set ANNUAL1 markMCQQ.If f(x) = |x|/x for x ≠ 0, and f(x) = 0 for x = 0, then lim(x→0) f(x) is:(a) 0(b) 1(c) -1(d) Does not exist
›Reveal solutionSolution
f(x)=∣x∣/x equals +1 for x>0 and −1 for x<0, so the left and right limits at 0 disagree.
For x>0: f(x)=xx=1, so x→0+limf(x)=1.
For x<0: f(x)=x−x=−1, so x→0−limf(x)=−1.
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- CBSE 2019Set annual1 markQ.If 'f' and 'g' are two real functions such that both limx→af(x) and limx→ag(x) exist, then limx→a[f(x)+g(x)]= ............... . (Fill in the blank)
›Reveal solutionSolution
By the algebra of limits, the limit of a sum of two functions is the sum of their individual limits (when both exist).
One of the standard limit laws states that if x→alimf(x) and x→alimg(x) both exist, then the limit of their sum exists and equals the sum of the limits:
limx→a[f(x)+g(x)]=limx→af(x)+limx→ag(x)
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