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\left(6-3x\right)\left(x+2\right)=x^{2}
Use the distributive property to multiply 3 by 2-x.
12-3x^{2}=x^{2}
Use the distributive property to multiply 6-3x by x+2 and combine like terms.
12-3x^{2}-x^{2}=0
Subtract x^{2} from both sides.
12-4x^{2}=0
Combine -3x^{2} and -x^{2} to get -4x^{2}.
-4x^{2}=-12
Subtract 12 from both sides. Anything subtracted from zero gives its negation.
x^{2}=\frac{-12}{-4}
Divide both sides by -4.
x^{2}=3
Divide -12 by -4 to get 3.
x=\sqrt{3} x=-\sqrt{3}
Take the square root of both sides of the equation.
\left(6-3x\right)\left(x+2\right)=x^{2}
Use the distributive property to multiply 3 by 2-x.
12-3x^{2}=x^{2}
Use the distributive property to multiply 6-3x by x+2 and combine like terms.
12-3x^{2}-x^{2}=0
Subtract x^{2} from both sides.
12-4x^{2}=0
Combine -3x^{2} and -x^{2} to get -4x^{2}.
-4x^{2}+12=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(-4\right)\times 12}}{2\left(-4\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -4 for a, 0 for b, and 12 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-4\right)\times 12}}{2\left(-4\right)}
Square 0.
x=\frac{0±\sqrt{16\times 12}}{2\left(-4\right)}
Multiply -4 times -4.
x=\frac{0±\sqrt{192}}{2\left(-4\right)}
Multiply 16 times 12.
x=\frac{0±8\sqrt{3}}{2\left(-4\right)}
Take the square root of 192.
x=\frac{0±8\sqrt{3}}{-8}
Multiply 2 times -4.
x=-\sqrt{3}
Now solve the equation x=\frac{0±8\sqrt{3}}{-8} when ± is plus.
x=\sqrt{3}
Now solve the equation x=\frac{0±8\sqrt{3}}{-8} when ± is minus.
x=-\sqrt{3} x=\sqrt{3}
The equation is now solved.