Solve for x
x=-4
Graph
Share
Copied to clipboard
2\times 6-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Variable x cannot be equal to any of the values -2,2 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-2\right)\left(x+2\right), the least common multiple of x^{2}-4,2-x,2x+4.
12-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Multiply 2 and 6 to get 12.
12-\left(-6x-4-2x^{2}\right)=\left(x-2\right)x
Use the distributive property to multiply -4-2x by x+1 and combine like terms.
12+6x+4+2x^{2}=\left(x-2\right)x
To find the opposite of -6x-4-2x^{2}, find the opposite of each term.
16+6x+2x^{2}=\left(x-2\right)x
Add 12 and 4 to get 16.
16+6x+2x^{2}=x^{2}-2x
Use the distributive property to multiply x-2 by x.
16+6x+2x^{2}-x^{2}=-2x
Subtract x^{2} from both sides.
16+6x+x^{2}=-2x
Combine 2x^{2} and -x^{2} to get x^{2}.
16+6x+x^{2}+2x=0
Add 2x to both sides.
16+8x+x^{2}=0
Combine 6x and 2x to get 8x.
x^{2}+8x+16=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=8 ab=16
To solve the equation, factor x^{2}+8x+16 using formula x^{2}+\left(a+b\right)x+ab=\left(x+a\right)\left(x+b\right). To find a and b, set up a system to be solved.
1,16 2,8 4,4
Since ab is positive, a and b have the same sign. Since a+b is positive, a and b are both positive. List all such integer pairs that give product 16.
1+16=17 2+8=10 4+4=8
Calculate the sum for each pair.
a=4 b=4
The solution is the pair that gives sum 8.
\left(x+4\right)\left(x+4\right)
Rewrite factored expression \left(x+a\right)\left(x+b\right) using the obtained values.
\left(x+4\right)^{2}
Rewrite as a binomial square.
x=-4
To find equation solution, solve x+4=0.
2\times 6-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Variable x cannot be equal to any of the values -2,2 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-2\right)\left(x+2\right), the least common multiple of x^{2}-4,2-x,2x+4.
12-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Multiply 2 and 6 to get 12.
12-\left(-6x-4-2x^{2}\right)=\left(x-2\right)x
Use the distributive property to multiply -4-2x by x+1 and combine like terms.
12+6x+4+2x^{2}=\left(x-2\right)x
To find the opposite of -6x-4-2x^{2}, find the opposite of each term.
16+6x+2x^{2}=\left(x-2\right)x
Add 12 and 4 to get 16.
16+6x+2x^{2}=x^{2}-2x
Use the distributive property to multiply x-2 by x.
16+6x+2x^{2}-x^{2}=-2x
Subtract x^{2} from both sides.
16+6x+x^{2}=-2x
Combine 2x^{2} and -x^{2} to get x^{2}.
16+6x+x^{2}+2x=0
Add 2x to both sides.
16+8x+x^{2}=0
Combine 6x and 2x to get 8x.
x^{2}+8x+16=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=8 ab=1\times 16=16
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as x^{2}+ax+bx+16. To find a and b, set up a system to be solved.
1,16 2,8 4,4
Since ab is positive, a and b have the same sign. Since a+b is positive, a and b are both positive. List all such integer pairs that give product 16.
1+16=17 2+8=10 4+4=8
Calculate the sum for each pair.
a=4 b=4
The solution is the pair that gives sum 8.
\left(x^{2}+4x\right)+\left(4x+16\right)
Rewrite x^{2}+8x+16 as \left(x^{2}+4x\right)+\left(4x+16\right).
x\left(x+4\right)+4\left(x+4\right)
Factor out x in the first and 4 in the second group.
\left(x+4\right)\left(x+4\right)
Factor out common term x+4 by using distributive property.
\left(x+4\right)^{2}
Rewrite as a binomial square.
x=-4
To find equation solution, solve x+4=0.
2\times 6-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Variable x cannot be equal to any of the values -2,2 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-2\right)\left(x+2\right), the least common multiple of x^{2}-4,2-x,2x+4.
12-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Multiply 2 and 6 to get 12.
12-\left(-6x-4-2x^{2}\right)=\left(x-2\right)x
Use the distributive property to multiply -4-2x by x+1 and combine like terms.
12+6x+4+2x^{2}=\left(x-2\right)x
To find the opposite of -6x-4-2x^{2}, find the opposite of each term.
16+6x+2x^{2}=\left(x-2\right)x
Add 12 and 4 to get 16.
16+6x+2x^{2}=x^{2}-2x
Use the distributive property to multiply x-2 by x.
16+6x+2x^{2}-x^{2}=-2x
Subtract x^{2} from both sides.
16+6x+x^{2}=-2x
Combine 2x^{2} and -x^{2} to get x^{2}.
16+6x+x^{2}+2x=0
Add 2x to both sides.
16+8x+x^{2}=0
Combine 6x and 2x to get 8x.
x^{2}+8x+16=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{-8±\sqrt{8^{2}-4\times 16}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 8 for b, and 16 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-8±\sqrt{64-4\times 16}}{2}
Square 8.
x=\frac{-8±\sqrt{64-64}}{2}
Multiply -4 times 16.
x=\frac{-8±\sqrt{0}}{2}
Add 64 to -64.
x=-\frac{8}{2}
Take the square root of 0.
x=-4
Divide -8 by 2.
2\times 6-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Variable x cannot be equal to any of the values -2,2 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-2\right)\left(x+2\right), the least common multiple of x^{2}-4,2-x,2x+4.
12-\left(-4-2x\right)\left(x+1\right)=\left(x-2\right)x
Multiply 2 and 6 to get 12.
12-\left(-6x-4-2x^{2}\right)=\left(x-2\right)x
Use the distributive property to multiply -4-2x by x+1 and combine like terms.
12+6x+4+2x^{2}=\left(x-2\right)x
To find the opposite of -6x-4-2x^{2}, find the opposite of each term.
16+6x+2x^{2}=\left(x-2\right)x
Add 12 and 4 to get 16.
16+6x+2x^{2}=x^{2}-2x
Use the distributive property to multiply x-2 by x.
16+6x+2x^{2}-x^{2}=-2x
Subtract x^{2} from both sides.
16+6x+x^{2}=-2x
Combine 2x^{2} and -x^{2} to get x^{2}.
16+6x+x^{2}+2x=0
Add 2x to both sides.
16+8x+x^{2}=0
Combine 6x and 2x to get 8x.
8x+x^{2}=-16
Subtract 16 from both sides. Anything subtracted from zero gives its negation.
x^{2}+8x=-16
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.
x^{2}+8x+4^{2}=-16+4^{2}
Divide 8, the coefficient of the x term, by 2 to get 4. Then add the square of 4 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+8x+16=-16+16
Square 4.
x^{2}+8x+16=0
Add -16 to 16.
\left(x+4\right)^{2}=0
Factor x^{2}+8x+16. 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+4\right)^{2}}=\sqrt{0}
Take the square root of both sides of the equation.
x+4=0 x+4=0
Simplify.
x=-4 x=-4
Subtract 4 from both sides of the equation.
x=-4
The equation is now solved. Solutions are the same.
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}