Math Homework

My calc homework confuses me, please help.

Question:
y= x^2
y= - x^2 + 2x - 5

Find the equations of two lines that are simultaneously tangent to both parabolas.

>>2
fail.


set the derivatives of the two eqns equal to each other, solve for x.

m = y'(x)  -- the x is the one you just solved for


plug in the same x into the two eqns. you will get 2 y's. the same x is the x0 below. the two y's are y0 below. plug x0 and y0 two times into the point slope eqn below. you will get two lines.

y - y0 = m (x - x0)