The trick to these problems and any “disguised quadratic”
is to recognize that it is a

disguised quadratic. Notice that in every problem of this type, there is a
relationship

between the leading term and the middle term! The power of the leading term is
double

that of the middle term.

Once you have recognized that the problem is a disguised
quadratic, you should make the

substitution u = middle ex pression .

Here are some examples:

Once you have made the correct substitution, you should have a quadratic
equation . Now

you can try to factor or use the quadratic formula .