Question 1202241
f(x) = x^2-1  x=3 find equation of tangent at x=3

Find the tangent point at x=3. Plug x=3 

we get 3^2-1 =8

The tangent point is (3,8)

Find slope of x^2-1 

dy/dx = 2x = 2*3 =6

y= mx+b equation of straight line
plug(3,8) and slope 6

8=6*3+b
b= 8-18
b=10

The equation of tangent 
y = 6x -10

*[illustration tangent_to_parabola.png].