Solve for x
x=-2
x=8
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24+4x-8-x\left(x-2\right)=0
Use the distributive property to multiply 4 by x-2.
16+4x-x\left(x-2\right)=0
Subtract 8 from 24 to get 16.
16+4x-\left(x^{2}-2x\right)=0
Use the distributive property to multiply x by x-2.
16+4x-x^{2}-\left(-2x\right)=0
To find the opposite of x^{2}-2x, find the opposite of each term.
16+4x-x^{2}+2x=0
The opposite of -2x is 2x.
16+6x-x^{2}=0
Combine 4x and 2x to get 6x.
-x^{2}+6x+16=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=6 ab=-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 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 -16.
-1+16=15 -2+8=6 -4+4=0
Calculate the sum for each pair.
a=8 b=-2
The solution is the pair that gives sum 6.
\left(-x^{2}+8x\right)+\left(-2x+16\right)
Rewrite -x^{2}+6x+16 as \left(-x^{2}+8x\right)+\left(-2x+16\right).
-x\left(x-8\right)-2\left(x-8\right)
Factor out -x in the first and -2 in the second group.
\left(x-8\right)\left(-x-2\right)
Factor out common term x-8 by using distributive property.
x=8 x=-2
To find equation solutions, solve x-8=0 and -x-2=0.
24+4x-8-x\left(x-2\right)=0
Use the distributive property to multiply 4 by x-2.
16+4x-x\left(x-2\right)=0
Subtract 8 from 24 to get 16.
16+4x-\left(x^{2}-2x\right)=0
Use the distributive property to multiply x by x-2.
16+4x-x^{2}-\left(-2x\right)=0
To find the opposite of x^{2}-2x, find the opposite of each term.
16+4x-x^{2}+2x=0
The opposite of -2x is 2x.
16+6x-x^{2}=0
Combine 4x and 2x to get 6x.
-x^{2}+6x+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{-6±\sqrt{6^{2}-4\left(-1\right)\times 16}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, 6 for b, and 16 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-6±\sqrt{36-4\left(-1\right)\times 16}}{2\left(-1\right)}
Square 6.
x=\frac{-6±\sqrt{36+4\times 16}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{-6±\sqrt{36+64}}{2\left(-1\right)}
Multiply 4 times 16.
x=\frac{-6±\sqrt{100}}{2\left(-1\right)}
Add 36 to 64.
x=\frac{-6±10}{2\left(-1\right)}
Take the square root of 100.
x=\frac{-6±10}{-2}
Multiply 2 times -1.
x=\frac{4}{-2}
Now solve the equation x=\frac{-6±10}{-2} when ± is plus. Add -6 to 10.
x=-2
Divide 4 by -2.
x=-\frac{16}{-2}
Now solve the equation x=\frac{-6±10}{-2} when ± is minus. Subtract 10 from -6.
x=8
Divide -16 by -2.
x=-2 x=8
The equation is now solved.
24+4x-8-x\left(x-2\right)=0
Use the distributive property to multiply 4 by x-2.
16+4x-x\left(x-2\right)=0
Subtract 8 from 24 to get 16.
16+4x-\left(x^{2}-2x\right)=0
Use the distributive property to multiply x by x-2.
16+4x-x^{2}-\left(-2x\right)=0
To find the opposite of x^{2}-2x, find the opposite of each term.
16+4x-x^{2}+2x=0
The opposite of -2x is 2x.
16+6x-x^{2}=0
Combine 4x and 2x to get 6x.
6x-x^{2}=-16
Subtract 16 from both sides. Anything subtracted from zero gives its negation.
-x^{2}+6x=-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.
\frac{-x^{2}+6x}{-1}=-\frac{16}{-1}
Divide both sides by -1.
x^{2}+\frac{6}{-1}x=-\frac{16}{-1}
Dividing by -1 undoes the multiplication by -1.
x^{2}-6x=-\frac{16}{-1}
Divide 6 by -1.
x^{2}-6x=16
Divide -16 by -1.
x^{2}-6x+\left(-3\right)^{2}=16+\left(-3\right)^{2}
Divide -6, the coefficient of the x term, by 2 to get -3. Then add the square of -3 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-6x+9=16+9
Square -3.
x^{2}-6x+9=25
Add 16 to 9.
\left(x-3\right)^{2}=25
Factor x^{2}-6x+9. 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-3\right)^{2}}=\sqrt{25}
Take the square root of both sides of the equation.
x-3=5 x-3=-5
Simplify.
x=8 x=-2
Add 3 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}