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x=\frac{x^{2}-2x}{5}
Add 2 and 3 to get 5.
x=\frac{1}{5}x^{2}-\frac{2}{5}x
Divide each term of x^{2}-2x by 5 to get \frac{1}{5}x^{2}-\frac{2}{5}x.
x-\frac{1}{5}x^{2}=-\frac{2}{5}x
Subtract \frac{1}{5}x^{2} from both sides.
x-\frac{1}{5}x^{2}+\frac{2}{5}x=0
Add \frac{2}{5}x to both sides.
\frac{7}{5}x-\frac{1}{5}x^{2}=0
Combine x and \frac{2}{5}x to get \frac{7}{5}x.
x\left(\frac{7}{5}-\frac{1}{5}x\right)=0
Factor out x.
x=0 x=7
To find equation solutions, solve x=0 and \frac{7-x}{5}=0.
x=\frac{x^{2}-2x}{5}
Add 2 and 3 to get 5.
x=\frac{1}{5}x^{2}-\frac{2}{5}x
Divide each term of x^{2}-2x by 5 to get \frac{1}{5}x^{2}-\frac{2}{5}x.
x-\frac{1}{5}x^{2}=-\frac{2}{5}x
Subtract \frac{1}{5}x^{2} from both sides.
x-\frac{1}{5}x^{2}+\frac{2}{5}x=0
Add \frac{2}{5}x to both sides.
\frac{7}{5}x-\frac{1}{5}x^{2}=0
Combine x and \frac{2}{5}x to get \frac{7}{5}x.
-\frac{1}{5}x^{2}+\frac{7}{5}x=0
All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. The quadratic formula gives two solutions, one when ± is addition and one when it is subtraction.
x=\frac{-\frac{7}{5}±\sqrt{\left(\frac{7}{5}\right)^{2}}}{2\left(-\frac{1}{5}\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -\frac{1}{5} for a, \frac{7}{5} for b, and 0 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\frac{7}{5}±\frac{7}{5}}{2\left(-\frac{1}{5}\right)}
Take the square root of \left(\frac{7}{5}\right)^{2}.
x=\frac{-\frac{7}{5}±\frac{7}{5}}{-\frac{2}{5}}
Multiply 2 times -\frac{1}{5}.
x=\frac{0}{-\frac{2}{5}}
Now solve the equation x=\frac{-\frac{7}{5}±\frac{7}{5}}{-\frac{2}{5}} when ± is plus. Add -\frac{7}{5} to \frac{7}{5} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
x=0
Divide 0 by -\frac{2}{5} by multiplying 0 by the reciprocal of -\frac{2}{5}.
x=-\frac{\frac{14}{5}}{-\frac{2}{5}}
Now solve the equation x=\frac{-\frac{7}{5}±\frac{7}{5}}{-\frac{2}{5}} when ± is minus. Subtract \frac{7}{5} from -\frac{7}{5} by finding a common denominator and subtracting the numerators. Then reduce the fraction to lowest terms if possible.
x=7
Divide -\frac{14}{5} by -\frac{2}{5} by multiplying -\frac{14}{5} by the reciprocal of -\frac{2}{5}.
x=0 x=7
The equation is now solved.
x=\frac{x^{2}-2x}{5}
Add 2 and 3 to get 5.
x=\frac{1}{5}x^{2}-\frac{2}{5}x
Divide each term of x^{2}-2x by 5 to get \frac{1}{5}x^{2}-\frac{2}{5}x.
x-\frac{1}{5}x^{2}=-\frac{2}{5}x
Subtract \frac{1}{5}x^{2} from both sides.
x-\frac{1}{5}x^{2}+\frac{2}{5}x=0
Add \frac{2}{5}x to both sides.
\frac{7}{5}x-\frac{1}{5}x^{2}=0
Combine x and \frac{2}{5}x to get \frac{7}{5}x.
-\frac{1}{5}x^{2}+\frac{7}{5}x=0
Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.
\frac{-\frac{1}{5}x^{2}+\frac{7}{5}x}{-\frac{1}{5}}=\frac{0}{-\frac{1}{5}}
Multiply both sides by -5.
x^{2}+\frac{\frac{7}{5}}{-\frac{1}{5}}x=\frac{0}{-\frac{1}{5}}
Dividing by -\frac{1}{5} undoes the multiplication by -\frac{1}{5}.
x^{2}-7x=\frac{0}{-\frac{1}{5}}
Divide \frac{7}{5} by -\frac{1}{5} by multiplying \frac{7}{5} by the reciprocal of -\frac{1}{5}.
x^{2}-7x=0
Divide 0 by -\frac{1}{5} by multiplying 0 by the reciprocal of -\frac{1}{5}.
x^{2}-7x+\left(-\frac{7}{2}\right)^{2}=\left(-\frac{7}{2}\right)^{2}
Divide -7, the coefficient of the x term, by 2 to get -\frac{7}{2}. Then add the square of -\frac{7}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-7x+\frac{49}{4}=\frac{49}{4}
Square -\frac{7}{2} by squaring both the numerator and the denominator of the fraction.
\left(x-\frac{7}{2}\right)^{2}=\frac{49}{4}
Factor x^{2}-7x+\frac{49}{4}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.
\sqrt{\left(x-\frac{7}{2}\right)^{2}}=\sqrt{\frac{49}{4}}
Take the square root of both sides of the equation.
x-\frac{7}{2}=\frac{7}{2} x-\frac{7}{2}=-\frac{7}{2}
Simplify.
x=7 x=0
Add \frac{7}{2} to both sides of the equation.