SOLUTION: Find the values for b such that the trinomial is a square x^2+bx+9 I worked the problem and of the 4 possible answers I believe 3 are correct (3/2, -3/2) or (12) or (3,-3

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: Find the values for b such that the trinomial is a square x^2+bx+9 I worked the problem and of the 4 possible answers I believe 3 are correct (3/2, -3/2) or (12) or (3,-3      Log On


   

Question 779428: Find the values for b such that the trinomial is a square
x^2+bx+9
I worked the problem and of the 4 possible answers I believe 3 are correct
(3/2, -3/2) or (12) or (3,-3) but only one can be
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2Bbx%2B9=0
In order for the left side to be a square, the "b" must be twice the square root of the 9. (This comes from %28x%2Bp%29%5E2+=+x%5E2%2B2px%2Bp%5E2

Since 9 has two square roots, 3 and -3, there will be two b's: 2*3 or 6 and 2*(-3) or -6.

So the values for b that make the trinomial a square are 6 and -6.