Question

Use suitable identity to evaluate
$99 {}^{2}$
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Answer 1

$\mathfrak \blue{as \: we \: are \: able \: to \: write \: 99 \: as \: 100 - 1}$

$\mathfrak \green{using \: the \: algebraic \: identity } \\ \tt{(a - b) {}^{2} = {a }^{2} + {b}^{2} - 2ab } \\ \tt \purple{substituting \: the \: values \: according \: to \: the \: formula} \\ \tt \pink{(100 - 1) {}^{2} = {100}^{2} + {1}^{2} - 2(100)(1) } \\ \tt {(100 - 1) {}^{2} = 10000 + 1 - 200 = 9801}$

Hope my answer will help you.