Question

If $(x+2)$ is a factor of the polynomial $f\left(x\right)=x^2+ax+2b$ and $a+b=4$, then the value of $a$ and $b$ are

• A. $a=1$, $b=3$
• B. $a=3$, $b=1$
• C. $a=-1$, $b=5$
• D. $a=5$, $b=-1$

Answer 1

Answer: (B)

$a=3$, $b=1$

$(-2{)}^2+a(-2)+2b=0$
$-2a+2b=-4$
$a-b=2$
$a+b=4$
$a=3$, $b=1$