SOLUTION: We are having trouble factoring on this problem: 12y^2-24y-72 We took out the 12 and got 12(y^2-2y-6) We can't think of any factors of -6 that would give a -2. Is there a solut

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: We are having trouble factoring on this problem: 12y^2-24y-72 We took out the 12 and got 12(y^2-2y-6) We can't think of any factors of -6 that would give a -2. Is there a solut      Log On


   

Question 134968: We are having trouble factoring on this problem:
12y^2-24y-72
We took out the 12 and got 12(y^2-2y-6) We can't think of any factors of -6 that would give a -2. Is there a solution, or do you think it was typed incorrectly on the worksheet? Thank you!
PS. This didn't come from a textbook, but from a teacher-created worksheet.
Found 2 solutions by vleith, stanbon:
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Use the quadratic formula.
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a =1, b = -2, c =-6

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
We are having trouble factoring on this problem:
12y^2-24y-72
= 12(y^2-2y-6)
Factoring y^2-2y-6 with the quadratic formula:
y = [2 +- sqrt(4 -4*1*-6)]/2
y = [2 +- sqrt(28)]/2
y = [1 +- sqrt7]
Factors are 12, (y-(1+sqrt7)), (y-(1-sqrt(7))
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Cheers,
Stan H.