Question

Plz explain this which is given in the attachment step by step and where it is used and why it is used ....

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Answer 1

$a^2+\dfrac {1}{a^2}+2\\\\\\=a^2+\dfrac {1}{a^2}+2\cdot a\cdot\dfrac {1}{a}\\\\\\=\mathbf {\left (a+\dfrac {1}{a}\right)^2}\\\\\\\\\text {Similarly,}\\\\\\a^2+\dfrac {1}{a^2}-2\\\\\\=a^2+\dfrac {1}{a^2}-2\cdot a\cdot\dfrac {1}{a}\\\\\\=\mathbf {\left (a-\dfrac {1}{a}\right)^2}$