Solve for x
x=\frac{1}{3}\approx 0.333333333
x=2
Graph
Share
Copied to clipboard
x^{2}-4-\left(7x-2x^{2}-6\right)=0
Use the distributive property to multiply x-2 by 3-2x and combine like terms.
x^{2}-4-7x+2x^{2}+6=0
To find the opposite of 7x-2x^{2}-6, find the opposite of each term.
3x^{2}-4-7x+6=0
Combine x^{2} and 2x^{2} to get 3x^{2}.
3x^{2}+2-7x=0
Add -4 and 6 to get 2.
3x^{2}-7x+2=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=-7 ab=3\times 2=6
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as 3x^{2}+ax+bx+2. To find a and b, set up a system to be solved.
-1,-6 -2,-3
Since ab is positive, a and b have the same sign. Since a+b is negative, a and b are both negative. List all such integer pairs that give product 6.
-1-6=-7 -2-3=-5
Calculate the sum for each pair.
a=-6 b=-1
The solution is the pair that gives sum -7.
\left(3x^{2}-6x\right)+\left(-x+2\right)
Rewrite 3x^{2}-7x+2 as \left(3x^{2}-6x\right)+\left(-x+2\right).
3x\left(x-2\right)-\left(x-2\right)
Factor out 3x in the first and -1 in the second group.
\left(x-2\right)\left(3x-1\right)
Factor out common term x-2 by using distributive property.
x=2 x=\frac{1}{3}
To find equation solutions, solve x-2=0 and 3x-1=0.
x^{2}-4-\left(7x-2x^{2}-6\right)=0
Use the distributive property to multiply x-2 by 3-2x and combine like terms.
x^{2}-4-7x+2x^{2}+6=0
To find the opposite of 7x-2x^{2}-6, find the opposite of each term.
3x^{2}-4-7x+6=0
Combine x^{2} and 2x^{2} to get 3x^{2}.
3x^{2}+2-7x=0
Add -4 and 6 to get 2.
3x^{2}-7x+2=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(-7\right)±\sqrt{\left(-7\right)^{2}-4\times 3\times 2}}{2\times 3}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 3 for a, -7 for b, and 2 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-7\right)±\sqrt{49-4\times 3\times 2}}{2\times 3}
Square -7.
x=\frac{-\left(-7\right)±\sqrt{49-12\times 2}}{2\times 3}
Multiply -4 times 3.
x=\frac{-\left(-7\right)±\sqrt{49-24}}{2\times 3}
Multiply -12 times 2.
x=\frac{-\left(-7\right)±\sqrt{25}}{2\times 3}
Add 49 to -24.
x=\frac{-\left(-7\right)±5}{2\times 3}
Take the square root of 25.
x=\frac{7±5}{2\times 3}
The opposite of -7 is 7.
x=\frac{7±5}{6}
Multiply 2 times 3.
x=\frac{12}{6}
Now solve the equation x=\frac{7±5}{6} when ± is plus. Add 7 to 5.
x=2
Divide 12 by 6.
x=\frac{2}{6}
Now solve the equation x=\frac{7±5}{6} when ± is minus. Subtract 5 from 7.
x=\frac{1}{3}
Reduce the fraction \frac{2}{6} to lowest terms by extracting and canceling out 2.
x=2 x=\frac{1}{3}
The equation is now solved.
x^{2}-4-\left(7x-2x^{2}-6\right)=0
Use the distributive property to multiply x-2 by 3-2x and combine like terms.
x^{2}-4-7x+2x^{2}+6=0
To find the opposite of 7x-2x^{2}-6, find the opposite of each term.
3x^{2}-4-7x+6=0
Combine x^{2} and 2x^{2} to get 3x^{2}.
3x^{2}+2-7x=0
Add -4 and 6 to get 2.
3x^{2}-7x=-2
Subtract 2 from both sides. Anything subtracted from zero gives its negation.
\frac{3x^{2}-7x}{3}=-\frac{2}{3}
Divide both sides by 3.
x^{2}-\frac{7}{3}x=-\frac{2}{3}
Dividing by 3 undoes the multiplication by 3.
x^{2}-\frac{7}{3}x+\left(-\frac{7}{6}\right)^{2}=-\frac{2}{3}+\left(-\frac{7}{6}\right)^{2}
Divide -\frac{7}{3}, the coefficient of the x term, by 2 to get -\frac{7}{6}. Then add the square of -\frac{7}{6} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{7}{3}x+\frac{49}{36}=-\frac{2}{3}+\frac{49}{36}
Square -\frac{7}{6} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{7}{3}x+\frac{49}{36}=\frac{25}{36}
Add -\frac{2}{3} to \frac{49}{36} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{7}{6}\right)^{2}=\frac{25}{36}
Factor x^{2}-\frac{7}{3}x+\frac{49}{36}. 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}{6}\right)^{2}}=\sqrt{\frac{25}{36}}
Take the square root of both sides of the equation.
x-\frac{7}{6}=\frac{5}{6} x-\frac{7}{6}=-\frac{5}{6}
Simplify.
x=2 x=\frac{1}{3}
Add \frac{7}{6} 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}