Hello.

Am stuck at this problem in saperable equations' section in my book.

Problem: Solve the differential equationby making the change of variable.

My solution:

I did not see any similar problems in my class' lectures and in the book's section.

All what I can do it is rewrite it as:

.

I put "?" because I do not know how to express in terms of u. i.e, expressing it using the suggested substiution.

Any help??