How to solve
The tangent line passes through (a, f(a)) with slope f'(a): y = f(a) + f'(a)(x − a).
Steps
- Compute f(a) — the point.
- Compute f'(a) — the slope.
- Assemble y = mx + b with b = f(a) − f'(a)·a.
Example
f(x) = x². Tangent at x = 3?
- f(3) = 9, f'(3) = 6.
- y = 9 + 6(x − 3) = 6x − 9.
Answer: y=6x-9
How to type answers
- Type it like y=6x-9
Loading drills…