Posted by Marty on .
x^4 + x^2  20
Help! I have no clue how to factor this! Do i have to square root everything?

Math 
mathstudent,
(x^2 + 5)(x^2  4)
If you set y = x^2 and look at the original as:
y^2 + y  20
It should factor easily to
(y + 5)(y  4)
which equals:
(x^2 + 5)(x^2  4) 
Math 
Marty,
so would the final answer be (x^2 + 5)(x^2  4) or (y + 5)(y  4) ???

Math 
mathstudent,
The final answer is
(x^2 + 5)(x^2  4)
If you multiply that, you will get your original equation.