I am trying to find the x an dtrhe y intercept of the graph of y+16-4x^2. I don't think there is an x intercept but my book says there is. How do you find it?

watch your typing, I am sure you meant

y = 16 - 4x^2

This is a parabola which opens downwards and has its vertex at (0,16), so it must surely cross the x-axis
for x-intercept, let y = 0
so
0 = 16 - 4x^2
easily solved to get x = ± 2