Solve for x
x = \frac{\sqrt{41} + 3}{2} \approx 4.701562119
x=\frac{3-\sqrt{41}}{2}\approx -1.701562119
Graph
Share
Copied to clipboard
\left(x+2\right)\left(x-4\right)=1x
Variable x cannot be equal to any of the values -3,-2 since division by zero is not defined. Multiply both sides of the equation by \left(x+2\right)\left(x+3\right), the least common multiple of x+3,x^{2}+5x+6.
x^{2}-2x-8=1x
Use the distributive property to multiply x+2 by x-4 and combine like terms.
x^{2}-2x-8-x=0
Subtract 1x from both sides.
x^{2}-3x-8=0
Combine -2x and -x to get -3x.
x=\frac{-\left(-3\right)±\sqrt{\left(-3\right)^{2}-4\left(-8\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, -3 for b, and -8 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-3\right)±\sqrt{9-4\left(-8\right)}}{2}
Square -3.
x=\frac{-\left(-3\right)±\sqrt{9+32}}{2}
Multiply -4 times -8.
x=\frac{-\left(-3\right)±\sqrt{41}}{2}
Add 9 to 32.
x=\frac{3±\sqrt{41}}{2}
The opposite of -3 is 3.
x=\frac{\sqrt{41}+3}{2}
Now solve the equation x=\frac{3±\sqrt{41}}{2} when ± is plus. Add 3 to \sqrt{41}.
x=\frac{3-\sqrt{41}}{2}
Now solve the equation x=\frac{3±\sqrt{41}}{2} when ± is minus. Subtract \sqrt{41} from 3.
x=\frac{\sqrt{41}+3}{2} x=\frac{3-\sqrt{41}}{2}
The equation is now solved.
\left(x+2\right)\left(x-4\right)=1x
Variable x cannot be equal to any of the values -3,-2 since division by zero is not defined. Multiply both sides of the equation by \left(x+2\right)\left(x+3\right), the least common multiple of x+3,x^{2}+5x+6.
x^{2}-2x-8=1x
Use the distributive property to multiply x+2 by x-4 and combine like terms.
x^{2}-2x-8-x=0
Subtract 1x from both sides.
x^{2}-3x-8=0
Combine -2x and -x to get -3x.
x^{2}-3x=8
Add 8 to both sides. Anything plus zero gives itself.
x^{2}-3x+\left(-\frac{3}{2}\right)^{2}=8+\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}=8+\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{41}{4}
Add 8 to \frac{9}{4}.
\left(x-\frac{3}{2}\right)^{2}=\frac{41}{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{41}{4}}
Take the square root of both sides of the equation.
x-\frac{3}{2}=\frac{\sqrt{41}}{2} x-\frac{3}{2}=-\frac{\sqrt{41}}{2}
Simplify.
x=\frac{\sqrt{41}+3}{2} x=\frac{3-\sqrt{41}}{2}
Add \frac{3}{2} 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}