# Math Help - tangent and secant

1. ## tangent and secant

Let f(x)=3^x-x^3. The tangent to the curve is parallel to the secant through (0,1) and (3,0) for x ~?

how do you go about to solve this?

2. Originally Posted by got_jane
Let f(x)=3^x-x^3. The tangent to the curve is parallel to the secant through (0,1) and (3,0) for x ~?

how do you go about to solve this?
The gradient of the line passing through (0,1) and (3,0) is 1/3. So solve f'(x) = 1/3 for x. Exact solutions are probably not possible .....

3. Originally Posted by mr fantastic
The gradient of the line passing through (0,1) and (3,0) is 1/3. So solve f'(x) = 1/3 for x. Exact solutions are probably not possible .....
so what can I do to approximate?

4. Originally Posted by got_jane
so what can I do to approximate?
You use whatever technology you have access to (graphics calculator, CAS calculator, software such as mathematica, derive etc.) in the appropriate way.