SOLUTION: I need to know if this is correct. Factor completely x^2 + 9x + 8 = (x+1)(x+8)

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I need to know if this is correct. Factor completely x^2 + 9x + 8 = (x+1)(x+8)      Log On


   

Question 107017: I need to know if this is correct. Factor completely
x^2 + 9x + 8 = (x+1)(x+8)
Answer by HyperBrain(694) About Me  (Show Source):
You can put this solution on YOUR website!
Read this lesson first---Factoring trinomials: SHORTCUT!!!

Then, go back to this page

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USing the quadratic formula,
x=%28-9%2B-sqrt%289%5E2-4%2A8%2A1%29%29%2F%282%2A1%29
x=%28-9%2B-sqrt%2881-32%29%29%2F%282%29
x=%28-9%2B-sqrt%2849%29%29%2F%282%29
x=%28-9%2B-+7%29%29%2F%282%29
x=%28-9%2B7%29%2F%282%29 or x=%28-9-7%29%2F%282%29
x=-2%2F2 or x=-16%2F2
x=-1 or x=-8
If x=-1, x%2B1=0
If x=-8, x%2B8=0

Therefore, x%5E2+%2B+9x+%2B+8+=+%28x%2B1%29%28x%2B8%29