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4-x^{2}=0
Variable x cannot be equal to -2 since division by zero is not defined. Multiply both sides of the equation by x+2.
-x^{2}=-4
Subtract 4 from both sides. Anything subtracted from zero gives its negation.
x^{2}=\frac{-4}{-1}
Divide both sides by -1.
x^{2}=4
Fraction \frac{-4}{-1} can be simplified to 4 by removing the negative sign from both the numerator and the denominator.
x=2 x=-2
Take the square root of both sides of the equation.
x=2
Variable x cannot be equal to -2.
4-x^{2}=0
Variable x cannot be equal to -2 since division by zero is not defined. Multiply both sides of the equation by x+2.
-x^{2}+4=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(-1\right)\times 4}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, 0 for b, and 4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-1\right)\times 4}}{2\left(-1\right)}
Square 0.
x=\frac{0±\sqrt{4\times 4}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{0±\sqrt{16}}{2\left(-1\right)}
Multiply 4 times 4.
x=\frac{0±4}{2\left(-1\right)}
Take the square root of 16.
x=\frac{0±4}{-2}
Multiply 2 times -1.
x=-2
Now solve the equation x=\frac{0±4}{-2} when ± is plus. Divide 4 by -2.
x=2
Now solve the equation x=\frac{0±4}{-2} when ± is minus. Divide -4 by -2.
x=-2 x=2
The equation is now solved.
x=2
Variable x cannot be equal to -2.