Solve for x
x=-4
x=1
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2x+x^{2}+x=4
Multiply both sides of the equation by 2.
3x+x^{2}=4
Combine 2x and x to get 3x.
3x+x^{2}-4=0
Subtract 4 from both sides.
x^{2}+3x-4=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=3 ab=-4
To solve the equation, factor x^{2}+3x-4 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.
-1,4 -2,2
Since ab is negative, a and b have the opposite signs. Since a+b is positive, the positive number has greater absolute value than the negative. List all such integer pairs that give product -4.
-1+4=3 -2+2=0
Calculate the sum for each pair.
a=-1 b=4
The solution is the pair that gives sum 3.
\left(x-1\right)\left(x+4\right)
Rewrite factored expression \left(x+a\right)\left(x+b\right) using the obtained values.
x=1 x=-4
To find equation solutions, solve x-1=0 and x+4=0.
2x+x^{2}+x=4
Multiply both sides of the equation by 2.
3x+x^{2}=4
Combine 2x and x to get 3x.
3x+x^{2}-4=0
Subtract 4 from both sides.
x^{2}+3x-4=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=3 ab=1\left(-4\right)=-4
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as x^{2}+ax+bx-4. To find a and b, set up a system to be solved.
-1,4 -2,2
Since ab is negative, a and b have the opposite signs. Since a+b is positive, the positive number has greater absolute value than the negative. List all such integer pairs that give product -4.
-1+4=3 -2+2=0
Calculate the sum for each pair.
a=-1 b=4
The solution is the pair that gives sum 3.
\left(x^{2}-x\right)+\left(4x-4\right)
Rewrite x^{2}+3x-4 as \left(x^{2}-x\right)+\left(4x-4\right).
x\left(x-1\right)+4\left(x-1\right)
Factor out x in the first and 4 in the second group.
\left(x-1\right)\left(x+4\right)
Factor out common term x-1 by using distributive property.
x=1 x=-4
To find equation solutions, solve x-1=0 and x+4=0.
2x+x^{2}+x=4
Multiply both sides of the equation by 2.
3x+x^{2}=4
Combine 2x and x to get 3x.
3x+x^{2}-4=0
Subtract 4 from both sides.
x^{2}+3x-4=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{-3±\sqrt{3^{2}-4\left(-4\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 3 for b, and -4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-3±\sqrt{9-4\left(-4\right)}}{2}
Square 3.
x=\frac{-3±\sqrt{9+16}}{2}
Multiply -4 times -4.
x=\frac{-3±\sqrt{25}}{2}
Add 9 to 16.
x=\frac{-3±5}{2}
Take the square root of 25.
x=\frac{2}{2}
Now solve the equation x=\frac{-3±5}{2} when ± is plus. Add -3 to 5.
x=1
Divide 2 by 2.
x=-\frac{8}{2}
Now solve the equation x=\frac{-3±5}{2} when ± is minus. Subtract 5 from -3.
x=-4
Divide -8 by 2.
x=1 x=-4
The equation is now solved.
2x+x^{2}+x=4
Multiply both sides of the equation by 2.
3x+x^{2}=4
Combine 2x and x to get 3x.
x^{2}+3x=4
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}+3x+\left(\frac{3}{2}\right)^{2}=4+\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}=4+\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{25}{4}
Add 4 to \frac{9}{4}.
\left(x+\frac{3}{2}\right)^{2}=\frac{25}{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{25}{4}}
Take the square root of both sides of the equation.
x+\frac{3}{2}=\frac{5}{2} x+\frac{3}{2}=-\frac{5}{2}
Simplify.
x=1 x=-4
Subtract \frac{3}{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}