Posted by meg on .
x^2+3x12=0
I need to factor this and thought I knew how, but I can't figure this one out. Factors of 12 are 1,12; 2,6; 3,4 and when I subtract these I don't get the 3 I need for the 3x. Am I overlooking something? My other problems were easy, so I don't think this would be a decimal or a fraction. Thank you for any help!!

algebra 
bobpursley,
lets do it by completion of the square:
x^2+3x+9/4=12+9/4
(x+3/2)^2=57/4
x=3/2+sqrt 14.25
so it factors, but into irrational numbers.
(x+1.5+sqrt 14.25)(x+1.5sqrt 14.25)=0
nice, huh?