Question

For what value of ${}^{\prime }{k}^{\prime },(k^2-4)x^2+2x-9=0$ can not be quadratic equation?

Answer 1

The given equation, $(k^2-4)x^2+2x-9=0$ will not be a quadratic one, if the co-efficient of $x^2$ is $0$.

Then we will have,

$k^2-4=0$

or, $k^2=4$

or, $k=\pm 2$.

So for $k=\pm 2$ the given equation will not be a quadratic equation.