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47-\left(3x^{2}+4x\right)=2\left(17-2x\right)-62
Use the distributive property to multiply x by 3x+4.
47-3x^{2}-4x=2\left(17-2x\right)-62
To find the opposite of 3x^{2}+4x, find the opposite of each term.
47-3x^{2}-4x=34-4x-62
Use the distributive property to multiply 2 by 17-2x.
47-3x^{2}-4x=-28-4x
Subtract 62 from 34 to get -28.
47-3x^{2}-4x+4x=-28
Add 4x to both sides.
47-3x^{2}=-28
Combine -4x and 4x to get 0.
-3x^{2}=-28-47
Subtract 47 from both sides.
-3x^{2}=-75
Subtract 47 from -28 to get -75.
x^{2}=\frac{-75}{-3}
Divide both sides by -3.
x^{2}=25
Divide -75 by -3 to get 25.
x=5 x=-5
Take the square root of both sides of the equation.
47-\left(3x^{2}+4x\right)=2\left(17-2x\right)-62
Use the distributive property to multiply x by 3x+4.
47-3x^{2}-4x=2\left(17-2x\right)-62
To find the opposite of 3x^{2}+4x, find the opposite of each term.
47-3x^{2}-4x=34-4x-62
Use the distributive property to multiply 2 by 17-2x.
47-3x^{2}-4x=-28-4x
Subtract 62 from 34 to get -28.
47-3x^{2}-4x-\left(-28\right)=-4x
Subtract -28 from both sides.
47-3x^{2}-4x+28=-4x
The opposite of -28 is 28.
47-3x^{2}-4x+28+4x=0
Add 4x to both sides.
75-3x^{2}-4x+4x=0
Add 47 and 28 to get 75.
75-3x^{2}=0
Combine -4x and 4x to get 0.
-3x^{2}+75=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(-3\right)\times 75}}{2\left(-3\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -3 for a, 0 for b, and 75 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-3\right)\times 75}}{2\left(-3\right)}
Square 0.
x=\frac{0±\sqrt{12\times 75}}{2\left(-3\right)}
Multiply -4 times -3.
x=\frac{0±\sqrt{900}}{2\left(-3\right)}
Multiply 12 times 75.
x=\frac{0±30}{2\left(-3\right)}
Take the square root of 900.
x=\frac{0±30}{-6}
Multiply 2 times -3.
x=-5
Now solve the equation x=\frac{0±30}{-6} when ± is plus. Divide 30 by -6.
x=5
Now solve the equation x=\frac{0±30}{-6} when ± is minus. Divide -30 by -6.
x=-5 x=5
The equation is now solved.