Question

$\\ (a+b)^{2} \\ \\ (a+b).(a-b)$

$\frac{(a+b)}{(a-b)}. \frac{(b-a)}{(b+a)}$

Answer 1

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$(a+b)^2=a^2+2ab+b^2 \\ \\ (a+b)(a-b)=a^2-b^2 \\ \\ \frac{a+b}{a-b} \times \frac{b-a}{b+a} = \\ \\ \frac{b-a}{a-b} = \frac{-1(a-b)}{a-b} =\fbox{ -1 }$