Solve for x
x=-5
x=8
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5\times 6=\left(x+2\right)\left(x-5\right)
Variable x cannot be equal to -2 since division by zero is not defined. Multiply both sides of the equation by 10\left(x+2\right), the least common multiple of 2x+4,10.
30=\left(x+2\right)\left(x-5\right)
Multiply 5 and 6 to get 30.
30=x^{2}-3x-10
Use the distributive property to multiply x+2 by x-5 and combine like terms.
x^{2}-3x-10=30
Swap sides so that all variable terms are on the left hand side.
x^{2}-3x-10-30=0
Subtract 30 from both sides.
x^{2}-3x-40=0
Subtract 30 from -10 to get -40.
x=\frac{-\left(-3\right)±\sqrt{\left(-3\right)^{2}-4\left(-40\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, -3 for b, and -40 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-3\right)±\sqrt{9-4\left(-40\right)}}{2}
Square -3.
x=\frac{-\left(-3\right)±\sqrt{9+160}}{2}
Multiply -4 times -40.
x=\frac{-\left(-3\right)±\sqrt{169}}{2}
Add 9 to 160.
x=\frac{-\left(-3\right)±13}{2}
Take the square root of 169.
x=\frac{3±13}{2}
The opposite of -3 is 3.
x=\frac{16}{2}
Now solve the equation x=\frac{3±13}{2} when ± is plus. Add 3 to 13.
x=8
Divide 16 by 2.
x=-\frac{10}{2}
Now solve the equation x=\frac{3±13}{2} when ± is minus. Subtract 13 from 3.
x=-5
Divide -10 by 2.
x=8 x=-5
The equation is now solved.
5\times 6=\left(x+2\right)\left(x-5\right)
Variable x cannot be equal to -2 since division by zero is not defined. Multiply both sides of the equation by 10\left(x+2\right), the least common multiple of 2x+4,10.
30=\left(x+2\right)\left(x-5\right)
Multiply 5 and 6 to get 30.
30=x^{2}-3x-10
Use the distributive property to multiply x+2 by x-5 and combine like terms.
x^{2}-3x-10=30
Swap sides so that all variable terms are on the left hand side.
x^{2}-3x=30+10
Add 10 to both sides.
x^{2}-3x=40
Add 30 and 10 to get 40.
x^{2}-3x+\left(-\frac{3}{2}\right)^{2}=40+\left(-\frac{3}{2}\right)^{2}
Divide -3, the coefficient of the x term, by 2 to get -\frac{3}{2}. Then add the square of -\frac{3}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-3x+\frac{9}{4}=40+\frac{9}{4}
Square -\frac{3}{2} by squaring both the numerator and the denominator of the fraction.
x^{2}-3x+\frac{9}{4}=\frac{169}{4}
Add 40 to \frac{9}{4}.
\left(x-\frac{3}{2}\right)^{2}=\frac{169}{4}
Factor x^{2}-3x+\frac{9}{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{3}{2}\right)^{2}}=\sqrt{\frac{169}{4}}
Take the square root of both sides of the equation.
x-\frac{3}{2}=\frac{13}{2} x-\frac{3}{2}=-\frac{13}{2}
Simplify.
x=8 x=-5
Add \frac{3}{2} to both sides of the equation.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
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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
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}