I have the question "Using the substitution given, integrate with respect to $x$"
Here is my working:

I understand everything expect for the bit after the word "hence".
If $6x^2$ cancels out, then where does the $\frac 16$ come from ?
I have the question "Using the substitution given, integrate with respect to $x$"
Here is my working:

I understand everything expect for the bit after the word "hence".
If $6x^2$ cancels out, then where does the $\frac 16$ come from ?
The integral after the word hence is incorrect. It should read $$ \int x^2 U^5 \frac{1}{6x^2} du $$ which should make it clear where the 1/6 comes from. In fact, I'm not sure why there was a $6x^2$ instead of an $x^2$ in that integral in the first place.