Solve for x
x = \frac{\sqrt{105} - 7}{2} \approx 1.623475383
x=\frac{-\sqrt{105}-7}{2}\approx -8.623475383
Graph
Share
Copied to clipboard
2\left(x-2\right)\left(x+4\right)-\left(-\left(2+x\right)x\right)=2x^{2}-x-2
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 \left(x-2\right)\left(x+2\right), the least common multiple of x+2,2-x,x^{2}-4.
\left(2x-4\right)\left(x+4\right)-\left(-\left(2+x\right)x\right)=2x^{2}-x-2
Use the distributive property to multiply 2 by x-2.
2x^{2}+4x-16-\left(-\left(2+x\right)x\right)=2x^{2}-x-2
Use the distributive property to multiply 2x-4 by x+4 and combine like terms.
2x^{2}+4x-16-\left(-2-x\right)x=2x^{2}-x-2
Use the distributive property to multiply -1 by 2+x.
2x^{2}+4x-16-\left(-2x-x^{2}\right)=2x^{2}-x-2
Use the distributive property to multiply -2-x by x.
2x^{2}+4x-16+2x+x^{2}=2x^{2}-x-2
To find the opposite of -2x-x^{2}, find the opposite of each term.
2x^{2}+6x-16+x^{2}=2x^{2}-x-2
Combine 4x and 2x to get 6x.
3x^{2}+6x-16=2x^{2}-x-2
Combine 2x^{2} and x^{2} to get 3x^{2}.
3x^{2}+6x-16-2x^{2}=-x-2
Subtract 2x^{2} from both sides.
x^{2}+6x-16=-x-2
Combine 3x^{2} and -2x^{2} to get x^{2}.
x^{2}+6x-16+x=-2
Add x to both sides.
x^{2}+7x-16=-2
Combine 6x and x to get 7x.
x^{2}+7x-16+2=0
Add 2 to both sides.
x^{2}+7x-14=0
Add -16 and 2 to get -14.
x=\frac{-7±\sqrt{7^{2}-4\left(-14\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 7 for b, and -14 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-7±\sqrt{49-4\left(-14\right)}}{2}
Square 7.
x=\frac{-7±\sqrt{49+56}}{2}
Multiply -4 times -14.
x=\frac{-7±\sqrt{105}}{2}
Add 49 to 56.
x=\frac{\sqrt{105}-7}{2}
Now solve the equation x=\frac{-7±\sqrt{105}}{2} when ± is plus. Add -7 to \sqrt{105}.
x=\frac{-\sqrt{105}-7}{2}
Now solve the equation x=\frac{-7±\sqrt{105}}{2} when ± is minus. Subtract \sqrt{105} from -7.
x=\frac{\sqrt{105}-7}{2} x=\frac{-\sqrt{105}-7}{2}
The equation is now solved.
2\left(x-2\right)\left(x+4\right)-\left(-\left(2+x\right)x\right)=2x^{2}-x-2
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 \left(x-2\right)\left(x+2\right), the least common multiple of x+2,2-x,x^{2}-4.
\left(2x-4\right)\left(x+4\right)-\left(-\left(2+x\right)x\right)=2x^{2}-x-2
Use the distributive property to multiply 2 by x-2.
2x^{2}+4x-16-\left(-\left(2+x\right)x\right)=2x^{2}-x-2
Use the distributive property to multiply 2x-4 by x+4 and combine like terms.
2x^{2}+4x-16-\left(-2-x\right)x=2x^{2}-x-2
Use the distributive property to multiply -1 by 2+x.
2x^{2}+4x-16-\left(-2x-x^{2}\right)=2x^{2}-x-2
Use the distributive property to multiply -2-x by x.
2x^{2}+4x-16+2x+x^{2}=2x^{2}-x-2
To find the opposite of -2x-x^{2}, find the opposite of each term.
2x^{2}+6x-16+x^{2}=2x^{2}-x-2
Combine 4x and 2x to get 6x.
3x^{2}+6x-16=2x^{2}-x-2
Combine 2x^{2} and x^{2} to get 3x^{2}.
3x^{2}+6x-16-2x^{2}=-x-2
Subtract 2x^{2} from both sides.
x^{2}+6x-16=-x-2
Combine 3x^{2} and -2x^{2} to get x^{2}.
x^{2}+6x-16+x=-2
Add x to both sides.
x^{2}+7x-16=-2
Combine 6x and x to get 7x.
x^{2}+7x=-2+16
Add 16 to both sides.
x^{2}+7x=14
Add -2 and 16 to get 14.
x^{2}+7x+\left(\frac{7}{2}\right)^{2}=14+\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}=14+\frac{49}{4}
Square \frac{7}{2} by squaring both the numerator and the denominator of the fraction.
x^{2}+7x+\frac{49}{4}=\frac{105}{4}
Add 14 to \frac{49}{4}.
\left(x+\frac{7}{2}\right)^{2}=\frac{105}{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{105}{4}}
Take the square root of both sides of the equation.
x+\frac{7}{2}=\frac{\sqrt{105}}{2} x+\frac{7}{2}=-\frac{\sqrt{105}}{2}
Simplify.
x=\frac{\sqrt{105}-7}{2} x=\frac{-\sqrt{105}-7}{2}
Subtract \frac{7}{2} from 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}