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8-x^{2}=x^{2}
Multiply both sides of the equation by 2.
8-x^{2}-x^{2}=0
Subtract x^{2} from both sides.
-x^{2}-x^{2}=-8
Subtract 8 from both sides. Anything subtracted from zero gives its negation.
-2x^{2}=-8
Combine -x^{2} and -x^{2} to get -2x^{2}.
x^{2}=\frac{-8}{-2}
Divide both sides by -2.
x^{2}=4
Divide -8 by -2 to get 4.
x=2 x=-2
Take the square root of both sides of the equation.
8-x^{2}=x^{2}
Multiply both sides of the equation by 2.
8-x^{2}-x^{2}=0
Subtract x^{2} from both sides.
8-2x^{2}=0
Combine -x^{2} and -x^{2} to get -2x^{2}.
-2x^{2}+8=0
Quadratic equations like this one, with an x^{2} term but no x term, can still be solved using the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}, once they are put in standard form: ax^{2}+bx+c=0.
x=\frac{0±\sqrt{0^{2}-4\left(-2\right)\times 8}}{2\left(-2\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -2 for a, 0 for b, and 8 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-2\right)\times 8}}{2\left(-2\right)}
Square 0.
x=\frac{0±\sqrt{8\times 8}}{2\left(-2\right)}
Multiply -4 times -2.
x=\frac{0±\sqrt{64}}{2\left(-2\right)}
Multiply 8 times 8.
x=\frac{0±8}{2\left(-2\right)}
Take the square root of 64.
x=\frac{0±8}{-4}
Multiply 2 times -2.
x=-2
Now solve the equation x=\frac{0±8}{-4} when ± is plus. Divide 8 by -4.
x=2
Now solve the equation x=\frac{0±8}{-4} when ± is minus. Divide -8 by -4.
x=-2 x=2
The equation is now solved.