Question

Simplify the expression $2(a^2+ab+3)$ - $ab$ and find its value when $a=5$ and $b=-3$.

• A. 2$a^2+3ab+3$ and 35
• B. 2$a^2+ab+3$ and 32
• C. 2$a^2+3ab+13$ and 37
• D. 2$a^2+ab+3$ and 38

Answer 1

The correct option is D 2$a^2+ab+3$ and 38

2($a^2+ab+3$) - $ab$
= $2a^2+2ab+3-ab$
= $2a^2+(2ab-ab)+3$
= $2a^2+ab+3$
Substituting $a=5$, $b=-3$ in the above expression,
$=2(5{)}^2+(5\left)\right(-3)+3=2(25)-15+3=50-15+3=38$