Question

Evaluate using identities
${87}^2$

Answer 1

${87}^2$

$=(90-3{)}^2$

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

$(90-3{)}^2={90}^2+3^2-2(90\left)\right(3)$

$=8100+9-540$

$=7569$

i.e; ${87}^2=7569$