SOLUTION: x^2-3x-28=0 work x^2 - 3x = 28 x^2 - x = 28/3

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Question 613860: x^2-3x-28=0
work
x^2 - 3x = 28
x^2 - x = 28/3
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2-3x-28=0 Start with the given equation.


Notice that the quadratic x%5E2-3x-28 is in the form of Ax%5E2%2BBx%2BC where A=1, B=-3, and C=-28


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-%28-3%29+%2B-+sqrt%28+%28-3%29%5E2-4%281%29%28-28%29+%29%29%2F%282%281%29%29 Plug in A=1, B=-3, and C=-28


x+=+%283+%2B-+sqrt%28+%28-3%29%5E2-4%281%29%28-28%29+%29%29%2F%282%281%29%29 Negate -3 to get 3.


x+=+%283+%2B-+sqrt%28+9-4%281%29%28-28%29+%29%29%2F%282%281%29%29 Square -3 to get 9.


x+=+%283+%2B-+sqrt%28+9--112+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-28%29 to get -112


x+=+%283+%2B-+sqrt%28+9%2B112+%29%29%2F%282%281%29%29 Rewrite sqrt%289--112%29 as sqrt%289%2B112%29


x+=+%283+%2B-+sqrt%28+121+%29%29%2F%282%281%29%29 Add 9 to 112 to get 121


x+=+%283+%2B-+sqrt%28+121+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%283+%2B-+11%29%2F%282%29 Take the square root of 121 to get 11.


x+=+%283+%2B+11%29%2F%282%29 or x+=+%283+-+11%29%2F%282%29 Break up the expression.


x+=+%2814%29%2F%282%29 or x+=++%28-8%29%2F%282%29 Combine like terms.


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


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


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