More random questions

[Salvadoramerican]

Find the value of x > 0 where the slope of the tangent line to f(x) = x^3-36x is x.
A. 2.81 B. 2.37 C. 3.63 D. 5.41 E. 4.03

1/(1-2x)=a0+a1x+a2x^2+a3x^3+... Find sum of ak where k=o to 5
A. 72 B. 63 C. 55 D. 31 E. 43
I know its an expansion but i never really got the topic.

[FabensMath]

The slope is the derivative, so the derivative of[unparseable or potentially dangerous latex formula] is [unparseable or potentially dangerous latex formula]
Set this equal to x and solve:
[unparseable or potentially dangerous latex formula] giving you x=3.63

[nsguy1350]

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula] [unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula], so B.63

[Salvadoramerican]

Thank you both