Question

Find all points of intersection: y=-x^2+4x and y=x^2

Answer 1

Equate both the equations to each other.
-x^2+4x=x^2
-2x^2+4x=0
2x(4-x)=0
x=0,4.
Point of y is for x =0 is y = 0

Answer 2

Sorry you factored it incorrectly.
2x(-x+2)=0
x=0 and x=2
(0,0) and (2,4) are the points of intersection.