# How do you use the rational root theorem to find the roots of #x^4 - 7x^2 + 12 = 0#?

##### 2 Answers

If

So

Since

Trying a few substitutions, we quickly find that

So the only rational roots are

George C gives a great answer to find that

If you need to find **all** (real or complex) roots, there a bit more work to do.

Because,

Divide by the factors using synthetic division or long division. Or divide by the product of these 2 factors,

You'll get

So the roots are: