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4x^{2}-x^{2}=240
Multiply both sides of the equation by 4.
3x^{2}=240
Combine 4x^{2} and -x^{2} to get 3x^{2}.
x^{2}=\frac{240}{3}
Divide both sides by 3.
x^{2}=80
Divide 240 by 3 to get 80.
x=4\sqrt{5} x=-4\sqrt{5}
Take the square root of both sides of the equation.
4x^{2}-x^{2}=240
Multiply both sides of the equation by 4.
4x^{2}-x^{2}-240=0
Subtract 240 from both sides.
3x^{2}-240=0
Combine 4x^{2} and -x^{2} to get 3x^{2}.
x=\frac{0±\sqrt{0^{2}-4\times 3\left(-240\right)}}{2\times 3}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 3 for a, 0 for b, and -240 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times 3\left(-240\right)}}{2\times 3}
Square 0.
x=\frac{0±\sqrt{-12\left(-240\right)}}{2\times 3}
Multiply -4 times 3.
x=\frac{0±\sqrt{2880}}{2\times 3}
Multiply -12 times -240.
x=\frac{0±24\sqrt{5}}{2\times 3}
Take the square root of 2880.
x=\frac{0±24\sqrt{5}}{6}
Multiply 2 times 3.
x=4\sqrt{5}
Now solve the equation x=\frac{0±24\sqrt{5}}{6} when ± is plus.
x=-4\sqrt{5}
Now solve the equation x=\frac{0±24\sqrt{5}}{6} when ± is minus.
x=4\sqrt{5} x=-4\sqrt{5}
The equation is now solved.