Question

Using identities, evaluate ${8.9}^2$

• A. $79.21$
• B. $63.01$
• C. $48.61$
• D. $52$

Answer 1

The correct option is A $79.21$

${8.9}^2$
$=(9-0.1{)}^2$
Using,
$(a-b{)}^2=a^2-2ab+b^2$ we get,
$=9^2-2\left(9\right)\left(0.1\right)+{0.1}^2$
$=81-1.8+0.01$
$=79.21$