Solve for x
x = -\frac{4}{3} = -1\frac{1}{3} \approx -1.333333333
x=2
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x-6+2x^{2}-2=-x^{2}+3x
Subtract 2 from both sides.
x-8+2x^{2}=-x^{2}+3x
Subtract 2 from -6 to get -8.
x-8+2x^{2}+x^{2}=3x
Add x^{2} to both sides.
x-8+3x^{2}=3x
Combine 2x^{2} and x^{2} to get 3x^{2}.
x-8+3x^{2}-3x=0
Subtract 3x from both sides.
-2x-8+3x^{2}=0
Combine x and -3x to get -2x.
3x^{2}-2x-8=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=-2 ab=3\left(-8\right)=-24
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as 3x^{2}+ax+bx-8. To find a and b, set up a system to be solved.
1,-24 2,-12 3,-8 4,-6
Since ab is negative, a and b have the opposite signs. Since a+b is negative, the negative number has greater absolute value than the positive. List all such integer pairs that give product -24.
1-24=-23 2-12=-10 3-8=-5 4-6=-2
Calculate the sum for each pair.
a=-6 b=4
The solution is the pair that gives sum -2.
\left(3x^{2}-6x\right)+\left(4x-8\right)
Rewrite 3x^{2}-2x-8 as \left(3x^{2}-6x\right)+\left(4x-8\right).
3x\left(x-2\right)+4\left(x-2\right)
Factor out 3x in the first and 4 in the second group.
\left(x-2\right)\left(3x+4\right)
Factor out common term x-2 by using distributive property.
x=2 x=-\frac{4}{3}
To find equation solutions, solve x-2=0 and 3x+4=0.
x-6+2x^{2}-2=-x^{2}+3x
Subtract 2 from both sides.
x-8+2x^{2}=-x^{2}+3x
Subtract 2 from -6 to get -8.
x-8+2x^{2}+x^{2}=3x
Add x^{2} to both sides.
x-8+3x^{2}=3x
Combine 2x^{2} and x^{2} to get 3x^{2}.
x-8+3x^{2}-3x=0
Subtract 3x from both sides.
-2x-8+3x^{2}=0
Combine x and -3x to get -2x.
3x^{2}-2x-8=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{-\left(-2\right)±\sqrt{\left(-2\right)^{2}-4\times 3\left(-8\right)}}{2\times 3}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 3 for a, -2 for b, and -8 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-2\right)±\sqrt{4-4\times 3\left(-8\right)}}{2\times 3}
Square -2.
x=\frac{-\left(-2\right)±\sqrt{4-12\left(-8\right)}}{2\times 3}
Multiply -4 times 3.
x=\frac{-\left(-2\right)±\sqrt{4+96}}{2\times 3}
Multiply -12 times -8.
x=\frac{-\left(-2\right)±\sqrt{100}}{2\times 3}
Add 4 to 96.
x=\frac{-\left(-2\right)±10}{2\times 3}
Take the square root of 100.
x=\frac{2±10}{2\times 3}
The opposite of -2 is 2.
x=\frac{2±10}{6}
Multiply 2 times 3.
x=\frac{12}{6}
Now solve the equation x=\frac{2±10}{6} when ± is plus. Add 2 to 10.
x=2
Divide 12 by 6.
x=-\frac{8}{6}
Now solve the equation x=\frac{2±10}{6} when ± is minus. Subtract 10 from 2.
x=-\frac{4}{3}
Reduce the fraction \frac{-8}{6} to lowest terms by extracting and canceling out 2.
x=2 x=-\frac{4}{3}
The equation is now solved.
x-6+2x^{2}+x^{2}=2+3x
Add x^{2} to both sides.
x-6+3x^{2}=2+3x
Combine 2x^{2} and x^{2} to get 3x^{2}.
x-6+3x^{2}-3x=2
Subtract 3x from both sides.
-2x-6+3x^{2}=2
Combine x and -3x to get -2x.
-2x+3x^{2}=2+6
Add 6 to both sides.
-2x+3x^{2}=8
Add 2 and 6 to get 8.
3x^{2}-2x=8
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{3x^{2}-2x}{3}=\frac{8}{3}
Divide both sides by 3.
x^{2}-\frac{2}{3}x=\frac{8}{3}
Dividing by 3 undoes the multiplication by 3.
x^{2}-\frac{2}{3}x+\left(-\frac{1}{3}\right)^{2}=\frac{8}{3}+\left(-\frac{1}{3}\right)^{2}
Divide -\frac{2}{3}, the coefficient of the x term, by 2 to get -\frac{1}{3}. Then add the square of -\frac{1}{3} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{2}{3}x+\frac{1}{9}=\frac{8}{3}+\frac{1}{9}
Square -\frac{1}{3} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{2}{3}x+\frac{1}{9}=\frac{25}{9}
Add \frac{8}{3} to \frac{1}{9} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{1}{3}\right)^{2}=\frac{25}{9}
Factor x^{2}-\frac{2}{3}x+\frac{1}{9}. 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{1}{3}\right)^{2}}=\sqrt{\frac{25}{9}}
Take the square root of both sides of the equation.
x-\frac{1}{3}=\frac{5}{3} x-\frac{1}{3}=-\frac{5}{3}
Simplify.
x=2 x=-\frac{4}{3}
Add \frac{1}{3} to both sides of the equation.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
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}