Question

find the square of 8.7 using identity

Answer 1

Dear student
$$\begin{gathered} 8.7^2 \\ ={\left(8+0.7\right)}^2 \\ =8^2+0.7^2+2\left(8\right)\left(0.7\right)\left[\because a^2+b^2+2ab={\left(a+b\right)}^2\right] \\ =64+0.49+11.2 \\ =75.69 \end{gathered}$$
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