3: The tangent line has slope
kT = f ′(1) = 0.
Its equation is
The normal line has slope
kN = −1/f ′(1) = −1/0 = ∞?
(Is it plus or minus
infinity?) This tells us that the normal line is vertical.
After all, the tangent line came up horizontal, so it makes sense.
Its equation is
Answer