posted by Drew on .
Find the x-coordinates of all points on the graph of y = x^3 - 4x^2 + 5x at which the tangent line is parallel to 2y - 10x - 7 = 0
the slope of the given line is 5
so find dy/dx for the cubic
and set that result equal to 5
you will get a quadratic which factors nicely.
let me know what values of x you got.
I got x=10/3 and x=6
3x^2 - 8x + 5 = 5
x(3x-8) = 0
x = 0 or x = 8/3
I don't understand how you got your answers.