SOLUTION: Whar is the roots? 2x^2+9x-5=0

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Question 580522: Whar is the roots? 2x^2+9x-5=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

2x%5E2%2B9x-5=0 Start with the given equation.


Notice that the quadratic 2x%5E2%2B9x-5 is in the form of Ax%5E2%2BBx%2BC where A=2, B=9, and C=-5


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-%289%29+%2B-+sqrt%28+%289%29%5E2-4%282%29%28-5%29+%29%29%2F%282%282%29%29 Plug in A=2, B=9, and C=-5


x+=+%28-9+%2B-+sqrt%28+81-4%282%29%28-5%29+%29%29%2F%282%282%29%29 Square 9 to get 81.


x+=+%28-9+%2B-+sqrt%28+81--40+%29%29%2F%282%282%29%29 Multiply 4%282%29%28-5%29 to get -40


x+=+%28-9+%2B-+sqrt%28+81%2B40+%29%29%2F%282%282%29%29 Rewrite sqrt%2881--40%29 as sqrt%2881%2B40%29


x+=+%28-9+%2B-+sqrt%28+121+%29%29%2F%282%282%29%29 Add 81 to 40 to get 121


x+=+%28-9+%2B-+sqrt%28+121+%29%29%2F%284%29 Multiply 2 and 2 to get 4.


x+=+%28-9+%2B-+11%29%2F%284%29 Take the square root of 121 to get 11.


x+=+%28-9+%2B+11%29%2F%284%29 or x+=+%28-9+-+11%29%2F%284%29 Break up the expression.


x+=+%282%29%2F%284%29 or x+=++%28-20%29%2F%284%29 Combine like terms.


x+=+1%2F2 or x+=+-5 Simplify.


So the solutions are x+=+1%2F2 or x+=+-5