So I've got -5x^2+20x+2, and have to determine the x intercepts.

I can use partial factoring to get -5x(x-4)+2

from which I can get

0=-5x

0/-5=x

0=x

AND

0=x-4

4=x

Which gives me 0 and 4.

My issues that when I enter -5x^2+20x+2 into a graphing calculator, the x-intercept coordinates I am given are -0.098 and 4.098. I'd like to know why. Have I done something wrong?

Thanks so much for the help!