Skip to content
NCERT Exemplar · Q6

Q.Given R={(x,y):x,y∈W, x2+y2=25}R = \{(x, y) : x, y \in \mathbf{W},\ x^2 + y^2 = 25\}. Find the domain and Range of RR.

Puducherry CbseShort· 2mImportance★★★★★est
64% · 64/100 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

The relation RR consists of pairs of whole numbers (x,y)(x, y) such that x2+y2=25x^2 + y^2 = 25. By systematically checking whole number values for xx from 00 to 55, we find the pairs (0,5),(3,4),(4,3),(5,0)(0, 5), (3, 4), (4, 3), (5, 0). The domain is {0,3,4,5}\{0, 3, 4, 5\} and the range is {0,3,4,5}\{0, 3, 4, 5\}.

Let's break down what the problem asks for and how to approach it.

A relation is simply a set of ordered pairs (x,y)(x, y) that satisfy a given condition. In this problem, the condition is x2+y2=25x^2 + y^2 = 25, and the elements xx and yy must belong to the set of whole numbers, W\mathbf{W}.

The domain of a relation is the set of all first elements (the xx-values) of the ordered pairs in the relation.

The range of a relation is the set of all second elements (the yy-values) of the ordered pairs in the relation.

To find the domain and range, our primary task is to identify all the ordered pairs (x,y)(x, y) that satisfy the given condition. We can think of this as systematically "testing" possible values for xx and yy from the set W\mathbf{W} to see which ones fit the rule. While an arrow diagram is a visual representation of a relation, it's typically drawn after we've identified the specific ordered pairs. For a relation defined by an equation, the most direct approach is to list these pairs first.

Here's how we find the domain and range for the given relation:

  1. Understand the set of numbers involved:

    The problem states that x,y∈Wx, y \in \mathbf{W}. The set of whole numbers W\mathbf{W} includes all non-negative integers: {0,1,2,3,… }\{0, 1, 2, 3, \dots\}. This is a crucial piece of information, as it restricts our search for xx and yy values.

  2. Identify constraints on xx and yy from the equation:

    We have the equation x2+y2=25x^2 + y^2 = 25.

    Since xx and yy are whole numbers, x2x^2 and y2y^2 must also be non-negative.

    This implies:

    • x2≤25  ⟹  x≤25  ⟹  x≤5x^2 \le 25 \implies x \le \sqrt{25} \implies x \le 5.
    • y2≤25  ⟹  y≤25  ⟹  y≤5y^2 \le 25 \implies y \le \sqrt{25} \implies y \le 5. So, we only need to check whole number values for xx and yy from 00 to 55.
  3. Systematically find all ordered pairs (x,y)(x, y) that satisfy x2+y2=25x^2 + y^2 = 25:

    We can iterate through possible whole number values for xx from 00 to 55 and see if a corresponding whole number yy exists.

    • If x=0x = 0:

      02+y2=250^2 + y^2 = 25

      0+y2=250 + y^2 = 25

      y2=25y^2 = 25

      y=25=5y = \sqrt{25} = 5 (since y∈Wy \in \mathbf{W}, we take the positive root).

      This gives us the ordered pair (0,5)(0, 5).

    • If x=1x = 1:

      12+y2=251^2 + y^2 = 25

      1+y2=251 + y^2 = 25

      y2=24y^2 = 24

      y=24y = \sqrt{24}. This is not a whole number. So, no pair for x=1x=1.

    • If x=2x = 2:

      22+y2=252^2 + y^2 = 25

      4+y2=254 + y^2 = 25

      y2=21y^2 = 21

      y=21y = \sqrt{21}. This is not a whole number. So, no pair for x=2x=2.

    • If x=3x = 3:

      32+y2=253^2 + y^2 = 25 …

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.