SOLUTION: please help me solve this equation {{{2x^2+17x=-21}}}

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Question 236448: please help me solve this equation
2x%5E2%2B17x=-21
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

2x%5E2%2B17x=-21 Start with the given equation.


2x%5E2%2B17x%2B21=0 Add 21 to both sides.


Notice that the quadratic 2x%5E2%2B17x%2B21 is in the form of Ax%5E2%2BBx%2BC where A=2, B=17, and C=21


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-%2817%29+%2B-+sqrt%28+%2817%29%5E2-4%282%29%2821%29+%29%29%2F%282%282%29%29 Plug in A=2, B=17, and C=21


x+=+%28-17+%2B-+sqrt%28+289-4%282%29%2821%29+%29%29%2F%282%282%29%29 Square 17 to get 289.


x+=+%28-17+%2B-+sqrt%28+289-168+%29%29%2F%282%282%29%29 Multiply 4%282%29%2821%29 to get 168


x+=+%28-17+%2B-+sqrt%28+121+%29%29%2F%282%282%29%29 Subtract 168 from 289 to get 121


x+=+%28-17+%2B-+sqrt%28+121+%29%29%2F%284%29 Multiply 2 and 2 to get 4.


x+=+%28-17+%2B-+11%29%2F%284%29 Take the square root of 121 to get 11.


x+=+%28-17+%2B+11%29%2F%284%29 or x+=+%28-17+-+11%29%2F%284%29 Break up the expression.


x+=+%28-6%29%2F%284%29 or x+=++%28-28%29%2F%284%29 Combine like terms.


x+=+-3%2F2 or x+=+-7 Simplify.


So the solutions are x+=+-3%2F2 or x+=+-7