# For which real x-values lays the graph with equation y = -x^4 + 18x^2 - 17 under the x-axis? Thank you!

##### 1 Answer

#### Explanation:

1)You must find the zeros of the equation

This is a second-degree equation where the "x" is

Therefore the roots are:

Now we need to know in which direction the polynomium goes in the zeros For this we need the first derivative:

Therefore the polynomial grows in -sqrt(17); decresases in -1; groes in 1 and decreases in sqrt(17) (it gives a form of a M). Taking the obtained zeros we can say that its negative in: