Solve for x
x = -\frac{9}{4} = -2\frac{1}{4} = -2.25
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x^{2}-9-x\left(x+4\right)=0
Consider \left(x+3\right)\left(x-3\right). Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}. Square 3.
x^{2}-9-\left(x^{2}+4x\right)=0
Use the distributive property to multiply x by x+4.
x^{2}-9-x^{2}-4x=0
To find the opposite of x^{2}+4x, find the opposite of each term.
-9-4x=0
Combine x^{2} and -x^{2} to get 0.
-4x=9
Add 9 to both sides. Anything plus zero gives itself.
x=\frac{9}{-4}
Divide both sides by -4.
x=-\frac{9}{4}
Fraction \frac{9}{-4} can be rewritten as -\frac{9}{4} by extracting the negative sign.
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}