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Solve for x (complex solution)
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x^{2}=\left(6\sqrt{-21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Subtract 24 from 3 to get -21.
x^{2}=\left(6\sqrt{21}i\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Factor -21=21\left(-1\right). Rewrite the square root of the product \sqrt{21\left(-1\right)} as the product of square roots \sqrt{21}\sqrt{-1}. By definition, the square root of -1 is i.
x^{2}=\left(6i\sqrt{21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Multiply 6 and i to get 6i.
x^{2}=\left(6i\right)^{2}\left(\sqrt{21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Expand \left(6i\sqrt{21}\right)^{2}.
x^{2}=-36\left(\sqrt{21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Calculate 6i to the power of 2 and get -36.
x^{2}=-36\times 21-\left(3\sqrt{3}-12\right)^{2}
The square of \sqrt{21} is 21.
x^{2}=-756-\left(3\sqrt{3}-12\right)^{2}
Multiply -36 and 21 to get -756.
x^{2}=-756-\left(9\left(\sqrt{3}\right)^{2}-72\sqrt{3}+144\right)
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(3\sqrt{3}-12\right)^{2}.
x^{2}=-756-\left(9\times 3-72\sqrt{3}+144\right)
The square of \sqrt{3} is 3.
x^{2}=-756-\left(27-72\sqrt{3}+144\right)
Multiply 9 and 3 to get 27.
x^{2}=-756-\left(171-72\sqrt{3}\right)
Add 27 and 144 to get 171.
x^{2}=-756-171+72\sqrt{3}
To find the opposite of 171-72\sqrt{3}, find the opposite of each term.
x^{2}=-927+72\sqrt{3}
Subtract 171 from -756 to get -927.
x=3i\sqrt{103-8\sqrt{3}} x=-3i\sqrt{103-8\sqrt{3}}
The equation is now solved.
x^{2}=\left(6\sqrt{-21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Subtract 24 from 3 to get -21.
x^{2}=\left(6\sqrt{21}i\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Factor -21=21\left(-1\right). Rewrite the square root of the product \sqrt{21\left(-1\right)} as the product of square roots \sqrt{21}\sqrt{-1}. By definition, the square root of -1 is i.
x^{2}=\left(6i\sqrt{21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Multiply 6 and i to get 6i.
x^{2}=\left(6i\right)^{2}\left(\sqrt{21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Expand \left(6i\sqrt{21}\right)^{2}.
x^{2}=-36\left(\sqrt{21}\right)^{2}-\left(3\sqrt{3}-12\right)^{2}
Calculate 6i to the power of 2 and get -36.
x^{2}=-36\times 21-\left(3\sqrt{3}-12\right)^{2}
The square of \sqrt{21} is 21.
x^{2}=-756-\left(3\sqrt{3}-12\right)^{2}
Multiply -36 and 21 to get -756.
x^{2}=-756-\left(9\left(\sqrt{3}\right)^{2}-72\sqrt{3}+144\right)
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(3\sqrt{3}-12\right)^{2}.
x^{2}=-756-\left(9\times 3-72\sqrt{3}+144\right)
The square of \sqrt{3} is 3.
x^{2}=-756-\left(27-72\sqrt{3}+144\right)
Multiply 9 and 3 to get 27.
x^{2}=-756-\left(171-72\sqrt{3}\right)
Add 27 and 144 to get 171.
x^{2}=-756-171+72\sqrt{3}
To find the opposite of 171-72\sqrt{3}, find the opposite of each term.
x^{2}=-927+72\sqrt{3}
Subtract 171 from -756 to get -927.
x^{2}-\left(-927\right)=72\sqrt{3}
Subtract -927 from both sides.
x^{2}+927=72\sqrt{3}
The opposite of -927 is 927.
x^{2}+927-72\sqrt{3}=0
Subtract 72\sqrt{3} from both sides.
x=\frac{0±\sqrt{0^{2}-4\left(927-72\sqrt{3}\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and 927-72\sqrt{3} for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(927-72\sqrt{3}\right)}}{2}
Square 0.
x=\frac{0±\sqrt{288\sqrt{3}-3708}}{2}
Multiply -4 times 927-72\sqrt{3}.
x=\frac{0±6i\sqrt{103-8\sqrt{3}}}{2}
Take the square root of -3708+288\sqrt{3}.
x=3i\sqrt{103-8\sqrt{3}}
Now solve the equation x=\frac{0±6i\sqrt{103-8\sqrt{3}}}{2} when ± is plus.
x=-3i\sqrt{103-8\sqrt{3}}
Now solve the equation x=\frac{0±6i\sqrt{103-8\sqrt{3}}}{2} when ± is minus.
x=3i\sqrt{103-8\sqrt{3}} x=-3i\sqrt{103-8\sqrt{3}}
The equation is now solved.