SOLUTION: Solve by using quadratic formula x2 + 2x – 4 = 0

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Question 280180: Solve by using quadratic formula x2 + 2x – 4 = 0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2B2x-4=0 Start with the given equation.


Notice that the quadratic x%5E2%2B2x-4 is in the form of Ax%5E2%2BBx%2BC where A=1, B=2, and C=-4


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


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


x+=+%28-2+%2B-+sqrt%28+4--16+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-4%29 to get -16


x+=+%28-2+%2B-+sqrt%28+4%2B16+%29%29%2F%282%281%29%29 Rewrite sqrt%284--16%29 as sqrt%284%2B16%29


x+=+%28-2+%2B-+sqrt%28+20+%29%29%2F%282%281%29%29 Add 4 to 16 to get 20


x+=+%28-2+%2B-+sqrt%28+20+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-2+%2B-+2%2Asqrt%285%29%29%2F%282%29 Simplify the square root (note: If you need help with simplifying square roots, check out this solver)


x+=+%28-2%29%2F%282%29+%2B-+%282%2Asqrt%285%29%29%2F%282%29 Break up the fraction.


x+=+-1+%2B-+sqrt%285%29 Reduce.


x+=+-1%2Bsqrt%285%29 or x+=+-1-sqrt%285%29 Break up the expression.


So the solutions are x+=+-1%2Bsqrt%285%29 or x+=+-1-sqrt%285%29