Question

Using the identity, evaluate the following.
${215}^2-{205}^2$

Answer 1

We have,

${215}^2-{205}^2$

We know that

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

$=(215-205)(215+205)$

$=10\times 420$

$=4200$

Hence, this is the answer.