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Solve for x (complex solution)
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20+\left(x^{2}+4\right)\times 4=0
Variable x cannot be equal to any of the values -2i,2i since division by zero is not defined. Multiply both sides of the equation by \left(x-2i\right)\left(x+2i\right).
20+4x^{2}+16=0
Use the distributive property to multiply x^{2}+4 by 4.
36+4x^{2}=0
Add 20 and 16 to get 36.
4x^{2}=-36
Subtract 36 from both sides. Anything subtracted from zero gives its negation.
x^{2}=\frac{-36}{4}
Divide both sides by 4.
x^{2}=-9
Divide -36 by 4 to get -9.
x=3i x=-3i
The equation is now solved.
20+\left(x^{2}+4\right)\times 4=0
Variable x cannot be equal to any of the values -2i,2i since division by zero is not defined. Multiply both sides of the equation by \left(x-2i\right)\left(x+2i\right).
20+4x^{2}+16=0
Use the distributive property to multiply x^{2}+4 by 4.
36+4x^{2}=0
Add 20 and 16 to get 36.
4x^{2}+36=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\times 4\times 36}}{2\times 4}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 4 for a, 0 for b, and 36 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times 4\times 36}}{2\times 4}
Square 0.
x=\frac{0±\sqrt{-16\times 36}}{2\times 4}
Multiply -4 times 4.
x=\frac{0±\sqrt{-576}}{2\times 4}
Multiply -16 times 36.
x=\frac{0±24i}{2\times 4}
Take the square root of -576.
x=\frac{0±24i}{8}
Multiply 2 times 4.
x=3i
Now solve the equation x=\frac{0±24i}{8} when ± is plus.
x=-3i
Now solve the equation x=\frac{0±24i}{8} when ± is minus.
x=3i x=-3i
The equation is now solved.