SOLUTION: using the quadratic formula x=[-b(+-)sqrt(b^2-4ac)]/2a solve quadratic equation x^2 -5 = 0

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Question 536619: using the quadratic formula x=[-b(+-)sqrt(b^2-4ac)]/2a
solve quadratic equation
x^2 -5 = 0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

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


Notice that the quadratic x%5E2-5 is in the form of Ax%5E2%2BBx%2BC where A=1, B=0, 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+=+%280+%2B-+sqrt%28+%280%29%5E2-4%281%29%28-5%29+%29%29%2F%282%281%29%29 Plug in A=1, B=0, and C=-5


x+=+%280+%2B-+sqrt%28+0-4%281%29%28-5%29+%29%29%2F%282%281%29%29 Square 0 to get 0.


x+=+%280+%2B-+sqrt%28+0--20+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-5%29 to get -20


x+=+%280+%2B-+sqrt%28+0%2B20+%29%29%2F%282%281%29%29 Rewrite sqrt%280--20%29 as sqrt%280%2B20%29


x+=+%280+%2B-+sqrt%28+20+%29%29%2F%282%281%29%29 Add 0 to 20 to get 20


x+=+%280+%2B-+sqrt%28+20+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%280+%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+=+%280%29%2F%282%29+%2B-+%282%2Asqrt%285%29%29%2F%282%29 Break up the fraction.


x+=+%22%22+%2B-+sqrt%285%29 Reduce.


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


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


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