Solve for x
x=2
x=\frac{1}{5}=0.2
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-5x\left(2x-5\right)=3x+4
Variable x cannot be equal to \frac{5}{2} since division by zero is not defined. Multiply both sides of the equation by 2x-5.
-10x^{2}+25x=3x+4
Use the distributive property to multiply -5x by 2x-5.
-10x^{2}+25x-3x=4
Subtract 3x from both sides.
-10x^{2}+22x=4
Combine 25x and -3x to get 22x.
-10x^{2}+22x-4=0
Subtract 4 from both sides.
x=\frac{-22±\sqrt{22^{2}-4\left(-10\right)\left(-4\right)}}{2\left(-10\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -10 for a, 22 for b, and -4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-22±\sqrt{484-4\left(-10\right)\left(-4\right)}}{2\left(-10\right)}
Square 22.
x=\frac{-22±\sqrt{484+40\left(-4\right)}}{2\left(-10\right)}
Multiply -4 times -10.
x=\frac{-22±\sqrt{484-160}}{2\left(-10\right)}
Multiply 40 times -4.
x=\frac{-22±\sqrt{324}}{2\left(-10\right)}
Add 484 to -160.
x=\frac{-22±18}{2\left(-10\right)}
Take the square root of 324.
x=\frac{-22±18}{-20}
Multiply 2 times -10.
x=-\frac{4}{-20}
Now solve the equation x=\frac{-22±18}{-20} when ± is plus. Add -22 to 18.
x=\frac{1}{5}
Reduce the fraction \frac{-4}{-20} to lowest terms by extracting and canceling out 4.
x=-\frac{40}{-20}
Now solve the equation x=\frac{-22±18}{-20} when ± is minus. Subtract 18 from -22.
x=2
Divide -40 by -20.
x=\frac{1}{5} x=2
The equation is now solved.
-5x\left(2x-5\right)=3x+4
Variable x cannot be equal to \frac{5}{2} since division by zero is not defined. Multiply both sides of the equation by 2x-5.
-10x^{2}+25x=3x+4
Use the distributive property to multiply -5x by 2x-5.
-10x^{2}+25x-3x=4
Subtract 3x from both sides.
-10x^{2}+22x=4
Combine 25x and -3x to get 22x.
\frac{-10x^{2}+22x}{-10}=\frac{4}{-10}
Divide both sides by -10.
x^{2}+\frac{22}{-10}x=\frac{4}{-10}
Dividing by -10 undoes the multiplication by -10.
x^{2}-\frac{11}{5}x=\frac{4}{-10}
Reduce the fraction \frac{22}{-10} to lowest terms by extracting and canceling out 2.
x^{2}-\frac{11}{5}x=-\frac{2}{5}
Reduce the fraction \frac{4}{-10} to lowest terms by extracting and canceling out 2.
x^{2}-\frac{11}{5}x+\left(-\frac{11}{10}\right)^{2}=-\frac{2}{5}+\left(-\frac{11}{10}\right)^{2}
Divide -\frac{11}{5}, the coefficient of the x term, by 2 to get -\frac{11}{10}. Then add the square of -\frac{11}{10} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{11}{5}x+\frac{121}{100}=-\frac{2}{5}+\frac{121}{100}
Square -\frac{11}{10} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{11}{5}x+\frac{121}{100}=\frac{81}{100}
Add -\frac{2}{5} to \frac{121}{100} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{11}{10}\right)^{2}=\frac{81}{100}
Factor x^{2}-\frac{11}{5}x+\frac{121}{100}. 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{11}{10}\right)^{2}}=\sqrt{\frac{81}{100}}
Take the square root of both sides of the equation.
x-\frac{11}{10}=\frac{9}{10} x-\frac{11}{10}=-\frac{9}{10}
Simplify.
x=2 x=\frac{1}{5}
Add \frac{11}{10} to both sides of the equation.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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Linear equation
y = 3x + 4
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Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}