# finding roots

• Dec 1st 2009, 10:10 AM
wolfhound
finding roots
how come I get different roots for
-5t^2 +25t -30 ?
by factorizing I get t=1 or t=-6
by -b formula I get t=2 or t=3?
• Dec 1st 2009, 10:19 AM
CaptainBlack
Quote:

Originally Posted by wolfhound
how come I get different roots for
-5t^2 +25t -30 ?
by factorizing I get t=1 or t=-6
by -b formula I get t=2 or t=3?

The formula roots are correct, the other roots are wrong, and if you don't tell us how you arrived at them we cannot tell you why.

(and you could have checked these yourself by substituting them back into the equation)

CB
• Dec 1st 2009, 10:22 AM
wolfhound
Quote:

Originally Posted by CaptainBlack
The formula roots are correct, the other roots are wrong, and if you don't tell us how you arrived at them we cannot tell you why.

(and you could have checked these yourself by substituting them back into the equation)

CB

I know now..I took 5 out as a common factor and then left -t^2 as a + t^2 instead of - resulting in wrong factoring thanks!