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Solve for x, y (complex solution)
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x+y=9
Solve x+y=9 for x by isolating x on the left hand side of the equal sign.
x=-y+9
Subtract y from both sides of the equation.
y^{2}+\left(-y+9\right)^{2}=27
Substitute -y+9 for x in the other equation, y^{2}+x^{2}=27.
y^{2}+y^{2}-18y+81=27
Square -y+9.
2y^{2}-18y+81=27
Add y^{2} to y^{2}.
2y^{2}-18y+54=0
Subtract 27 from both sides of the equation.
y=\frac{-\left(-18\right)±\sqrt{\left(-18\right)^{2}-4\times 2\times 54}}{2\times 2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1+1\left(-1\right)^{2} for a, 1\times 9\left(-1\right)\times 2 for b, and 54 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
y=\frac{-\left(-18\right)±\sqrt{324-4\times 2\times 54}}{2\times 2}
Square 1\times 9\left(-1\right)\times 2.
y=\frac{-\left(-18\right)±\sqrt{324-8\times 54}}{2\times 2}
Multiply -4 times 1+1\left(-1\right)^{2}.
y=\frac{-\left(-18\right)±\sqrt{324-432}}{2\times 2}
Multiply -8 times 54.
y=\frac{-\left(-18\right)±\sqrt{-108}}{2\times 2}
Add 324 to -432.
y=\frac{-\left(-18\right)±6\sqrt{3}i}{2\times 2}
Take the square root of -108.
y=\frac{18±6\sqrt{3}i}{2\times 2}
The opposite of 1\times 9\left(-1\right)\times 2 is 18.
y=\frac{18±6\sqrt{3}i}{4}
Multiply 2 times 1+1\left(-1\right)^{2}.
y=\frac{18+6\sqrt{3}i}{4}
Now solve the equation y=\frac{18±6\sqrt{3}i}{4} when ± is plus. Add 18 to 6i\sqrt{3}.
y=\frac{9+3\sqrt{3}i}{2}
Divide 18+6i\sqrt{3} by 4.
y=\frac{-6\sqrt{3}i+18}{4}
Now solve the equation y=\frac{18±6\sqrt{3}i}{4} when ± is minus. Subtract 6i\sqrt{3} from 18.
y=\frac{-3\sqrt{3}i+9}{2}
Divide 18-6i\sqrt{3} by 4.
x=-\frac{9+3\sqrt{3}i}{2}+9
There are two solutions for y: \frac{9+3i\sqrt{3}}{2} and \frac{9-3i\sqrt{3}}{2}. Substitute \frac{9+3i\sqrt{3}}{2} for y in the equation x=-y+9 to find the corresponding solution for x that satisfies both equations.
x=-\frac{-3\sqrt{3}i+9}{2}+9
Now substitute \frac{9-3i\sqrt{3}}{2} for y in the equation x=-y+9 and solve to find the corresponding solution for x that satisfies both equations.
x=-\frac{9+3\sqrt{3}i}{2}+9,y=\frac{9+3\sqrt{3}i}{2}\text{ or }x=-\frac{-3\sqrt{3}i+9}{2}+9,y=\frac{-3\sqrt{3}i+9}{2}
The system is now solved.