SOLUTION: x^2+40x-45=0

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Question 545459: x^2+40x-45=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2B40x-45=0 Start with the given equation.


Notice that the quadratic x%5E2%2B40x-45 is in the form of Ax%5E2%2BBx%2BC where A=1, B=40, and C=-45


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-%2840%29+%2B-+sqrt%28+%2840%29%5E2-4%281%29%28-45%29+%29%29%2F%282%281%29%29 Plug in A=1, B=40, and C=-45


x+=+%28-40+%2B-+sqrt%28+1600-4%281%29%28-45%29+%29%29%2F%282%281%29%29 Square 40 to get 1600.


x+=+%28-40+%2B-+sqrt%28+1600--180+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-45%29 to get -180


x+=+%28-40+%2B-+sqrt%28+1600%2B180+%29%29%2F%282%281%29%29 Rewrite sqrt%281600--180%29 as sqrt%281600%2B180%29


x+=+%28-40+%2B-+sqrt%28+1780+%29%29%2F%282%281%29%29 Add 1600 to 180 to get 1780


x+=+%28-40+%2B-+sqrt%28+1780+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-40+%2B-+2%2Asqrt%28445%29%29%2F%282%29 Simplify the square root (note: If you need help with simplifying square roots, check out this solver)


x+=+%28-40%29%2F%282%29+%2B-+%282%2Asqrt%28445%29%29%2F%282%29 Break up the fraction.


x+=+-20+%2B-+sqrt%28445%29 Reduce.


x+=+-20%2Bsqrt%28445%29 or x+=+-20-sqrt%28445%29 Break up the expression.


So the solutions are x+=+-20%2Bsqrt%28445%29 or x+=+-20-sqrt%28445%29