In vid 2, session 2, prof. finds 2x for tangent line when y=0. He finds y intercept (2y) by using symmetry. He says you can also find y int. by plugging zero in for x in the tangent line equation. I can't get 2y by plugging zero in for x. Any help?

Question

In vid 2, session 2, prof. finds 2x for tangent line when y=0.  He finds y intercept (2y) by using symmetry.  He says you can also find y int. by plugging zero in for x in the tangent line equation.  I can't get 2y by plugging zero in for x.  Any help?

anonymous · Answer

Got it!  The slope of the tangent actually comes out to be f(x), i.e., y-y0=y0, so y=2y0.  Hope this helps someone else.