Hello MHF, please help me with this problem
But isnt correct, i'm afraid my substitution is not correct
This is a difficult integral for someone who hasn't learned about u-substitution yet. You're probably aware that the derivative of is . And looking at the other term might eventually lead you to take the derivative of . Once you do that, you should be able to combine the two derivatives to get the expression you want to integrate.
It's probably less work to first learn u-substution, then apply it to this integral. But I guess that's not an option for you.