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\frac{4}{x-9}
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\frac{4}{x-9}
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\frac{3}{x+9}+\frac{x+63}{\left(x-9\right)\left(x+9\right)}
Factor x^{2}-81.
\frac{3\left(x-9\right)}{\left(x-9\right)\left(x+9\right)}+\frac{x+63}{\left(x-9\right)\left(x+9\right)}
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of x+9 and \left(x-9\right)\left(x+9\right) is \left(x-9\right)\left(x+9\right). Multiply \frac{3}{x+9} times \frac{x-9}{x-9}.
\frac{3\left(x-9\right)+x+63}{\left(x-9\right)\left(x+9\right)}
Since \frac{3\left(x-9\right)}{\left(x-9\right)\left(x+9\right)} and \frac{x+63}{\left(x-9\right)\left(x+9\right)} have the same denominator, add them by adding their numerators.
\frac{3x-27+x+63}{\left(x-9\right)\left(x+9\right)}
Do the multiplications in 3\left(x-9\right)+x+63.
\frac{4x+36}{\left(x-9\right)\left(x+9\right)}
Combine like terms in 3x-27+x+63.
\frac{4\left(x+9\right)}{\left(x-9\right)\left(x+9\right)}
Factor the expressions that are not already factored in \frac{4x+36}{\left(x-9\right)\left(x+9\right)}.
\frac{4}{x-9}
Cancel out x+9 in both numerator and denominator.
\frac{3}{x+9}+\frac{x+63}{\left(x-9\right)\left(x+9\right)}
Factor x^{2}-81.
\frac{3\left(x-9\right)}{\left(x-9\right)\left(x+9\right)}+\frac{x+63}{\left(x-9\right)\left(x+9\right)}
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of x+9 and \left(x-9\right)\left(x+9\right) is \left(x-9\right)\left(x+9\right). Multiply \frac{3}{x+9} times \frac{x-9}{x-9}.
\frac{3\left(x-9\right)+x+63}{\left(x-9\right)\left(x+9\right)}
Since \frac{3\left(x-9\right)}{\left(x-9\right)\left(x+9\right)} and \frac{x+63}{\left(x-9\right)\left(x+9\right)} have the same denominator, add them by adding their numerators.
\frac{3x-27+x+63}{\left(x-9\right)\left(x+9\right)}
Do the multiplications in 3\left(x-9\right)+x+63.
\frac{4x+36}{\left(x-9\right)\left(x+9\right)}
Combine like terms in 3x-27+x+63.
\frac{4\left(x+9\right)}{\left(x-9\right)\left(x+9\right)}
Factor the expressions that are not already factored in \frac{4x+36}{\left(x-9\right)\left(x+9\right)}.
\frac{4}{x-9}
Cancel out x+9 in both numerator and denominator.
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}