SOLUTION: use the quadratic formula to solve the equation 5x2(squared) -6x -8=0

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Question 208093: use the quadratic formula to solve the equation 5x2(squared) -6x -8=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

5x%5E2-6x-8=0 Start with the given equation.


Notice that the quadratic 5x%5E2-6x-8 is in the form of Ax%5E2%2BBx%2BC where A=5, B=-6, and C=-8


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-%28-6%29+%2B-+sqrt%28+%28-6%29%5E2-4%285%29%28-8%29+%29%29%2F%282%285%29%29 Plug in A=5, B=-6, and C=-8


x+=+%286+%2B-+sqrt%28+%28-6%29%5E2-4%285%29%28-8%29+%29%29%2F%282%285%29%29 Negate -6 to get 6.


x+=+%286+%2B-+sqrt%28+36-4%285%29%28-8%29+%29%29%2F%282%285%29%29 Square -6 to get 36.


x+=+%286+%2B-+sqrt%28+36--160+%29%29%2F%282%285%29%29 Multiply 4%285%29%28-8%29 to get -160


x+=+%286+%2B-+sqrt%28+36%2B160+%29%29%2F%282%285%29%29 Rewrite sqrt%2836--160%29 as sqrt%2836%2B160%29


x+=+%286+%2B-+sqrt%28+196+%29%29%2F%282%285%29%29 Add 36 to 160 to get 196


x+=+%286+%2B-+sqrt%28+196+%29%29%2F%2810%29 Multiply 2 and 5 to get 10.


x+=+%286+%2B-+14%29%2F%2810%29 Take the square root of 196 to get 14.


x+=+%286+%2B+14%29%2F%2810%29 or x+=+%286+-+14%29%2F%2810%29 Break up the expression.


x+=+%2820%29%2F%2810%29 or x+=++%28-8%29%2F%2810%29 Combine like terms.


x+=+2 or x+=+-4%2F5 Simplify.


So the solutions are x+=+2 or x+=+-4%2F5