4. Compute the derivative.
Find when the gradient is 7.
Evaluate at this point.
The point we want is then (2, 5).
5. The curve crosses the -axis when . We have
Compute the derivative.
At the point we want, the gradient is
6. The curve crosses the -axis when . Compute the derivative.
When , the gradient is
7. Set and solve for . The curve and line meet when
Compute the derivative (for the curve) and evaluate it at these values.
8. Compute the derivative.
The gradient is 8 when , so
and the gradient is -10 when , so
Solve for and . Eliminating , we have
so that
.