Using identities, evaluate $5 . 2^{2}$

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Solution

To Evaluate : $5 . 2^{2}$
$5 . 2^{2}$ can be written as ${(5 + 0.2)}^{2}$
Using the identity
${(a + b)}^{2} = a^{2} + b^{2} + 2 a b$
$\begin{array}{rcl} 5 . 2^{2} & = & {(5 + 0.2)}^{2} \\ {(5 + 0.2)}^{2} & = & 5^{2} + 0 . 2^{2} + 2 \times 5 \times 0.2 \\ {(5 + 0.2)}^{2} & = & 25 + 0.4 + 2 \\ {(5 + 0.2)}^{2} & = & 27.4 \end{array}$
$∴ 5 . 2^{2} = 27.4$

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{5.2}^{2}

{5.2}^{2}

Using identities, evaluate: ${5.2}^{2}$

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