# How do you factor x= y^2-21y-63 ?

##### 1 Answer
Jul 30, 2016

can't be factored

#### Explanation:

f(y) = y^2 - 21y - 63
D = b^2 - 4ac = 441 + 252 = 693.
Since D is not a perfect square, f(y) can't be factored.