Question:
Let R = [(x, y) : x, y ∈ Z, y = 2x − 4]. If (a, -2) and (4, b2) ∈ R, then write the values of a and b.
Solution:
R = [(x, y) : x, y ∈ Z, y = 2x − 4]
$(a,-2)$ and $\left(4, b^{2}\right) \in \mathrm{R}$
So, $-2=2($ a) $-4$
$\Rightarrow 2=2 a$
$\Rightarrow a=1$
Also, $b^{2}=2(4)-4$
$\Rightarrow b^{2}=4$
$\Rightarrow b=\pm 2$
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