There are two lines that pass through the point (5,10) and are tangent to the parabola
f(x) = -16+10x - x^2 .
Find the equations for both of them.
*So far I know that i should have something like
m(a) = [ f(a) -10 ] / [ a - 5 ] = f'(a)
and f'(a)= -2x+10
right? so how do I solve for a? I think that's what i'm supposed to be doing. and yeah I know also the derivative is f'(a)= -2x+10