Question 83001
Rearrange your equation like this: y=2x^2-8
And to find where the graph crosses the x-axis, put y=0 (because ALL points on the x-axis have a y-coordinate of 0)
So
2x^2-8=0
2x^2=8
x^2=4
x=2 or x=-2
{{{ graph( 300, 200, -4, 4, -10, 20, 2x^2-8 ) }}}