SOLUTION: I need help the question is multiple choice and I don't know how to solve it. The question asks: What are the zeros of {{{ f(x)=x^2+6x-55 }}} The choices are: A) -11,-5 B) -1

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I need help the question is multiple choice and I don't know how to solve it. The question asks: What are the zeros of {{{ f(x)=x^2+6x-55 }}} The choices are: A) -11,-5 B) -1      Log On


   

Question 677459: I need help the question is multiple choice and I don't know how to solve it.
The question asks: What are the zeros of +f%28x%29=x%5E2%2B6x-55+
The choices are:
A) -11,-5
B) -11, 5
C) -5, 11
D) 5, 11
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Use the quadratic formula

x+=+%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29

x+=+%28-%286%29%2B-sqrt%28%286%29%5E2-4%281%29%28-55%29%29%29%2F%282%281%29%29 ... Plug in a+=+1, b+=+6, c+=+-55

x+=+%28-6%2B-sqrt%2836-%28-220%29%29%29%2F%282%29

x+=+%28-6%2B-sqrt%2836%2B220%29%29%2F%282%29

x+=+%28-6%2B-sqrt%28256%29%29%2F2

x+=+%28-6%2Bsqrt%28256%29%29%2F2 or x+=+%28-6-sqrt%28256%29%29%2F2

x+=+%28-6%2B16%29%2F2 or x+=+%28-6-16%29%2F2

x+=+10%2F2 or x+=+-22%2F2

x+=+5 or x+=+-11

So the answer is choice B