Question

If $2$ is a zero of both the polynomial, $3x^2+ax-14$ and $2x-b$, then value of $(a-2b)$ is,

• A. -7
• B. -6
• C. -5
• D. -4

Answer 1

Answer: (A)

$(-7)$

Substitute the value of $x$ as $2$ in both the equations and equate it zero, as $2$ is zero of both the equations.
we will get, $3(2{)}^2+a(2)-14=0$ and $2\left(2\right)-b=0$,
$\Rightarrow 12+2a-14=0$ and $4-b=0$
$2a-2=0$ and $4=b$
$2a=2$
$\therefore a=1$, and $b=4$.

So, $a-2b=1-2\left(4\right)=1-8=-7$