Question

Can someone help me write y=-x^2-x+6 in intercept form?

Answer 1

What you've written here is a quadratic function. It doesn't have an "intercept form."
However, it does have a y-intercept: set x = 0 and you'll find that y=6.
So your y-intercept is (0,6). End of story.

Answer 2

Only straight lines have a "slope-intercept form."