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Question: Answered & Verified by Expert
If $\mathrm{R}=\{(a, \mathrm{~b}) / \mathrm{b}=a-1, a \in \mathrm{Z}, 5 < a < 9\}$, then the range of $\mathrm{R}$ is
MathematicsFunctionsMHT CETMHT CET 2020 (19 Oct Shift 2)
Options:
  • A $\{7,8,9\}$
  • B $\{5,6,7\}$
  • C $\{6,7,8\}$
  • D $\{5,6,7,8,9\}$
Solution:
2453 Upvotes Verified Answer
The correct answer is: $\{5,6,7\}$
(A)
Given $\mathbf{R}=\{(\mathbf{a}, \mathbf{b}), \mathbf{b}=\mathbf{a}-1, \mathbf{a} \in \mathbf{z}, 5 < \mathbf{a} < 9\}$
$\therefore \quad a=6,7,8$
$a=6, b=6-1=5$
$a=7, b=7-1=6$
$a=8, b=8-1=7$
$R=\{(6,5),(7,6),(8,7)\}$
Range of $R=\{5,6,7\}$

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