Question

The value of $(7.2{)}^2$ is (use an identity to expand):

• A. $49.9$
• B. $14.4$
• C. $51.84$
• D. $49.04$

Answer 1

The correct option is C $51.84$

We will use, $(a+b{)}^2$= $a^2+2ab+b^2$ to find the required result.

Substitute $7$ for $a$ and $0.2$ for $B$ in the above identity,

$(7+0.2{)}^2=(7{)}^2+2\left(7\right)\left(0.2\right)+(0.2{)}^2$

$=49+2.8+0.04$

$=51.84$

Hence, option $C$ is correct.