Solve for x
x=-13
x=6
Graph
Share
Copied to clipboard
\left(2x+24\right)\left(5x-16\right)+\left(9x+108\right)\left(3-x\right)=18
Variable x cannot be equal to -12 since division by zero is not defined. Multiply both sides of the equation by 18\left(x+12\right), the least common multiple of 9,2,x+12.
10x^{2}+88x-384+\left(9x+108\right)\left(3-x\right)=18
Use the distributive property to multiply 2x+24 by 5x-16 and combine like terms.
10x^{2}+88x-384-81x-9x^{2}+324=18
Use the distributive property to multiply 9x+108 by 3-x and combine like terms.
10x^{2}+7x-384-9x^{2}+324=18
Combine 88x and -81x to get 7x.
x^{2}+7x-384+324=18
Combine 10x^{2} and -9x^{2} to get x^{2}.
x^{2}+7x-60=18
Add -384 and 324 to get -60.
x^{2}+7x-60-18=0
Subtract 18 from both sides.
x^{2}+7x-78=0
Subtract 18 from -60 to get -78.
x=\frac{-7±\sqrt{7^{2}-4\left(-78\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 7 for b, and -78 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-7±\sqrt{49-4\left(-78\right)}}{2}
Square 7.
x=\frac{-7±\sqrt{49+312}}{2}
Multiply -4 times -78.
x=\frac{-7±\sqrt{361}}{2}
Add 49 to 312.
x=\frac{-7±19}{2}
Take the square root of 361.
x=\frac{12}{2}
Now solve the equation x=\frac{-7±19}{2} when ± is plus. Add -7 to 19.
x=6
Divide 12 by 2.
x=-\frac{26}{2}
Now solve the equation x=\frac{-7±19}{2} when ± is minus. Subtract 19 from -7.
x=-13
Divide -26 by 2.
x=6 x=-13
The equation is now solved.
\left(2x+24\right)\left(5x-16\right)+\left(9x+108\right)\left(3-x\right)=18
Variable x cannot be equal to -12 since division by zero is not defined. Multiply both sides of the equation by 18\left(x+12\right), the least common multiple of 9,2,x+12.
10x^{2}+88x-384+\left(9x+108\right)\left(3-x\right)=18
Use the distributive property to multiply 2x+24 by 5x-16 and combine like terms.
10x^{2}+88x-384-81x-9x^{2}+324=18
Use the distributive property to multiply 9x+108 by 3-x and combine like terms.
10x^{2}+7x-384-9x^{2}+324=18
Combine 88x and -81x to get 7x.
x^{2}+7x-384+324=18
Combine 10x^{2} and -9x^{2} to get x^{2}.
x^{2}+7x-60=18
Add -384 and 324 to get -60.
x^{2}+7x=18+60
Add 60 to both sides.
x^{2}+7x=78
Add 18 and 60 to get 78.
x^{2}+7x+\left(\frac{7}{2}\right)^{2}=78+\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}=78+\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{361}{4}
Add 78 to \frac{49}{4}.
\left(x+\frac{7}{2}\right)^{2}=\frac{361}{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{361}{4}}
Take the square root of both sides of the equation.
x+\frac{7}{2}=\frac{19}{2} x+\frac{7}{2}=-\frac{19}{2}
Simplify.
x=6 x=-13
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}