Question

Number of real roots of equation $x^4+x^2-12=0$ is

• A. 4
• B. 2
• C. 0
• D. 3

Answer 1

Answer: (B)

$x^4+x^2-12=0$
$\left(x^2+4\right)\left(x^2-3\right)=0$
$\Rightarrow x^2=-4\text{ or }{x}^2=3$
$x=\pm 2ix=\pm \sqrt{3}$
so number of real roots is 2