Question

Find the value of ${49}^2$ using standard identity.

• A. $2391$
• B. $2401$
• C. $2411$
• D. $2421$

Answer 1

Answer: (B)

$2401$

As we know that,

$(a-b{)}^2=a^2-2ab+b^2$

Substitute $50$ for $a$ and $1$ for $b$ in above formula,

$\begin{array}{cc}(50-1{)}^2& ={50}^2-2\times 50\times 1+1^2\\ {49}^2& =2500-100+1\\ & =2401\end{array}$

Therefore, $B$ is correct.