00:01
This looks really complicated, but it's a very doable problem.
00:05
So we have the cube root of x cubed, sorry, 3x cube plus 7, dx.
00:16
And you want to look for an interfunction to let you equal.
00:20
In this case, the 3x cube plus 7 is perfect.
00:25
And i know they tell you to do that, but the reason for that is because the derivative of that using a power rule.
00:33
Actually has something to do with the other piece that's in front.
00:36
And what i tell some students, because i think it's helpful, is to divide the 9 and the x squared over, because then what they can do is they can rewrite this integral.
00:46
It's equal to the same thing.
00:49
Maybe instead of writing the cube root, i can write it as a one -third power.
00:53
This inner piece is equal to u.
00:57
And then i can replace dx with that 1 over 9x squared du that i found down here...