Question

Using identities, evaluate: ${71}^2$

Answer 1

Given: ${71}^2$

Now, $71=70+1$

Therefore, ${71}^2=(70+1{)}^2$

Using identity, $(a+b{)}^2=a^2+b^2+2ab$, we get,

$\Rightarrow (70+1{)}^2={70}^2+1^2+2\times 70\times 1$

$=4900+1+1400$

$=5041$

Thus, $(70+1{)}^2=5041$