Find the equation of the tangent to the graph at the indicat

Find the equation of the tangent to the graph at the indicated point.f(x) = x2 2x; a = 8

Solution

f(x) = x2 2x

Slope of tangent to f(x) is

f\'(x) = 2x-2

at x=a=-8

f\'(-8) = -16-2 = -18

f(-8) = (-8)^2-2(-8) = 64+16 =80

Using slope-point form,

equation of tangent is,

y-80 = -18(x+8)

18x+y+64=0