f(x) = e^(3)x
g(x) = x^3
Point where f(x) and g(x) have parallel tangent lines?

Question

f(x) = e^(3)x
g(x) = x^3
Point where f(x) and g(x) have parallel tangent lines?

kc_kennylau · Answer

Tangent lines parallel = slope the same = derivative the same

kc_kennylau · Answer

Find the derivatives of the two functions and set them equal and solve for x and you'll have the answer

anonymous · Answer

The slope is the tangent line for a function at a given point.  Therefore, the problem can be rephrased as "find the point at which f(x) and g(x) have the same slope.  Slope is of course given by the derivative of a function.

anonymous · Answer

I equated them and solved but apparently that answer is not the same which is mentioned.

kc_kennylau · Answer

Show us your steps maybe?

anonymous · Answer

f'(x) = g'(x)
e^3 = 3x^2
x ~ +2.3 or -2.3
The answer which is given is -0.484

kc_kennylau · Answer

You sure it's (e^3)x not e^(3x)?

anonymous · Answer

Oh my bloody bad. It IS e^(3x) actually. *facepalm*

kc_kennylau · Answer

Then do it again lol

anonymous · Answer

Check how your derivative of e^3x.

anonymous · Answer

Yup it comes as -0.484 now.

kc_kennylau · Answer

you're welcome