Question

Using a suitable identity, evaluate ${31}^2$.

• A. 961

Answer 1

The correct option is A 961
Using the identity, $(a+b{)}^2=a^2+b^2+2ab$

${31}^2$ can be written as $(30+1{)}^2$.
Now, a = 30 and b = 1
$(30+1{)}^2={30}^2+1^2+2\times 30\times 1$
$=900+1+60$
$=961$