SOLUTION: solve for x 2x^2+6x-56=0

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Question 299538: solve for x
2x^2+6x-56=0


Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

2x%5E2%2B6x-56=0 Start with the given equation.


Notice that the quadratic 2x%5E2%2B6x-56 is in the form of Ax%5E2%2BBx%2BC where A=2, B=6, and C=-56


Let's use the quadratic formula to solve for "x":


x+=+%28-B+%2B-+sqrt%28+B%5E2-4AC+%29%29%2F%282A%29 Start with the quadratic formula


x+=+%28-%286%29+%2B-+sqrt%28+%286%29%5E2-4%282%29%28-56%29+%29%29%2F%282%282%29%29 Plug in A=2, B=6, and C=-56


x+=+%28-6+%2B-+sqrt%28+36-4%282%29%28-56%29+%29%29%2F%282%282%29%29 Square 6 to get 36.


x+=+%28-6+%2B-+sqrt%28+36--448+%29%29%2F%282%282%29%29 Multiply 4%282%29%28-56%29 to get -448


x+=+%28-6+%2B-+sqrt%28+36%2B448+%29%29%2F%282%282%29%29 Rewrite sqrt%2836--448%29 as sqrt%2836%2B448%29


x+=+%28-6+%2B-+sqrt%28+484+%29%29%2F%282%282%29%29 Add 36 to 448 to get 484


x+=+%28-6+%2B-+sqrt%28+484+%29%29%2F%284%29 Multiply 2 and 2 to get 4.


x+=+%28-6+%2B-+22%29%2F%284%29 Take the square root of 484 to get 22.


x+=+%28-6+%2B+22%29%2F%284%29 or x+=+%28-6+-+22%29%2F%284%29 Break up the expression.


x+=+%2816%29%2F%284%29 or x+=++%28-28%29%2F%284%29 Combine like terms.


x+=+4 or x+=+-7 Simplify.


So the solutions are x+=+4 or x+=+-7