Question

One of the zero of the polynomial $f\left(x\right)=2x^2+7x-4$ is

• A. $\frac{1}{2}$
• B. 2
• C. $\frac{1}{2}$
• D. -2

Answer 1

The correct option is A $\frac{1}{2}$

Given: $f\left(x\right)=2x^2+7x-4$

We know that if $f\left(a\right)=0;$ then $a$ is the zero of the polynomial $f\left(x\right)$.

$\therefore f\left(x\right)=0$
$\Rightarrow 2x^2+7x-4=0$
$\Rightarrow 2x^2+8x-x-4=0$
$\Rightarrow 2x(x+4)-1(x+4)=0$
$\Rightarrow (2x-1)(x+4)=0$
$\Rightarrow 2x=1orx+4=0$
$\Rightarrow x=\frac{1}{2}or-4$

$\because \frac{1}{2}$ is zero of $f\left(x\right)=2x^2+7x-4$

Hence, option (B) is the correct answer.