Hello, Becky!

Sorry, you made two omissions in the first step . . .

I proceeded this way:

3x+1)^3(2)(1-2x)" alt="f'(x)\:=\3x+1)^3(2)(1-2x)" />(-2)

. . . . . . . . . . all over denominator-squared

It should have looked like this:

. .

. . . . . .

Factor: .

. . . . . . .

. . . . . . .