Question

Find the value of ${22.9}^2-{7.1}^2$ using a suitable algebraic identity.

• A. 500
• B. 474
• C. 497
• D. 574

Answer 1

The correct option is B 474

Given, ${22.9}^2-{7.1}^2$.
It is in the form of $a^2-b^2$, where a = 22.9 and b = 7.1

Using the identity, $a^2-b^2=(a+b)(a-b)$,
we get

${22.9}^2-{7.1}^2$

$=(22.9+7.1)(22.9-7.1)$

$=\left(30\right)\left(15.8\right)$

$=474$