Solve for x
x=7
x=0
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0=x\left(1+13-2x\right)
Multiply 0 and 0 to get 0.
0=x\left(14-2x\right)
Add 1 and 13 to get 14.
0=14x-2x^{2}
Use the distributive property to multiply x by 14-2x.
14x-2x^{2}=0
Swap sides so that all variable terms are on the left hand side.
x\left(14-2x\right)=0
Factor out x.
x=0 x=7
To find equation solutions, solve x=0 and 14-2x=0.
0=x\left(1+13-2x\right)
Multiply 0 and 0 to get 0.
0=x\left(14-2x\right)
Add 1 and 13 to get 14.
0=14x-2x^{2}
Use the distributive property to multiply x by 14-2x.
14x-2x^{2}=0
Swap sides so that all variable terms are on the left hand side.
-2x^{2}+14x=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{-14±\sqrt{14^{2}}}{2\left(-2\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -2 for a, 14 for b, and 0 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-14±14}{2\left(-2\right)}
Take the square root of 14^{2}.
x=\frac{-14±14}{-4}
Multiply 2 times -2.
x=\frac{0}{-4}
Now solve the equation x=\frac{-14±14}{-4} when ± is plus. Add -14 to 14.
x=0
Divide 0 by -4.
x=-\frac{28}{-4}
Now solve the equation x=\frac{-14±14}{-4} when ± is minus. Subtract 14 from -14.
x=7
Divide -28 by -4.
x=0 x=7
The equation is now solved.
0=x\left(1+13-2x\right)
Multiply 0 and 0 to get 0.
0=x\left(14-2x\right)
Add 1 and 13 to get 14.
0=14x-2x^{2}
Use the distributive property to multiply x by 14-2x.
14x-2x^{2}=0
Swap sides so that all variable terms are on the left hand side.
-2x^{2}+14x=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{-2x^{2}+14x}{-2}=\frac{0}{-2}
Divide both sides by -2.
x^{2}+\frac{14}{-2}x=\frac{0}{-2}
Dividing by -2 undoes the multiplication by -2.
x^{2}-7x=\frac{0}{-2}
Divide 14 by -2.
x^{2}-7x=0
Divide 0 by -2.
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.
Examples
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Linear equation
y = 3x + 4
Arithmetic
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Matrix
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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
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