Question

Then value of $x$ in equation ${\left(72\right)}^2+x={\left(87\right)}^2$ is:

• A. 3278
• B. 2385
• C. 2475
• D. 2587

Answer 1

The correct option is B 2385

We have,

${72}^2+x={87}^2$

$x={87}^2-{72}^2$

We know that

$a^2-b^2=(a-b)(a+b)$

Therefore,

$x=(87-72)(87+72)$

$x=\left(15\right)\left(159\right)$

$x=2385$

Hence, this is the answer.