SOLUTION: Give exact and approximate solutions to three decimal places x^2+12x+36=64 How do I solve this?

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Give exact and approximate solutions to three decimal places x^2+12x+36=64 How do I solve this?      Log On


   

Question 478235: Give exact and approximate solutions to three decimal places
x^2+12x+36=64
How do I solve this?
Found 2 solutions by Alan3354, MathLover1:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2B12x%2B36=64
x%5E2%2B12x-28+=+0
(x+14)*(x-2) = 0
x = -14
x = 2
--------
That's one way

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2B12x%2B36=64...here you have a quadratic function and fist you need to write it in standard form ax%5E2%2Bbx%2Bc=0

x%5E2%2B12x%2B36-64=0

x%5E2%2B12x-28=0...now use a quadratic formula to find solutions
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+...note that a=1, b=12 and c=-28

x+=+%28-12+%2B-+sqrt%28+12%5E2-4%2A1%2A%28-28%29+%29%29%2F%282%2A1%29+
x+=+%28-12+%2B-+sqrt%28144%2B112%29%29%2F2+
x+=+%28-12+%2B-+sqrt%28256%29%29%2F2+
x+=+%28-12+%2B-+16%29%2F2+
solutions:
x+=+%28-12+%2B+16%29%2F2+
x+=+4%2F2+
x+=+2+
or
x+=+%28-12+-+16%29%2F2+
x+=+-28%2F2+
x+=+-14+
here is the graph:
+graph%28+500%2C+500%2C+-20%2C+20%2C+-50%2C+30%2Cx%5E2%2B12x-28%29+