Question

Let f be the function given by f(x)=(2x-1)^5(x+1). Which of the following is an equation for the line tangent to the graph of f at the point where x=1?

a) y=21x+2
b) y=21x-19
c) y=11x-9
d) y=10x+2
e) y=10x-8

I took the derivative and got (2x-1)^5+(2x-1)^4(10x+10) but how do I find it from there?

Answer 1

If you have f'(x), simply substitute x = 1 and you have the slope of the tangent line.

You have f(x), also. Substitute x = 1 and you have the y-coordinate of the needed point.

This gives point and slope and you are almost done.

Answer 2

Thanks.