Evaluate
-\frac{3x}{7}+\frac{4}{9x}
Factor
\frac{28-27x^{2}}{63x}
Graph
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\frac{4\times 7}{63x}-\frac{3x\times 9x}{63x}
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of 9x and 7 is 63x. Multiply \frac{4}{9x} times \frac{7}{7}. Multiply \frac{3x}{7} times \frac{9x}{9x}.
\frac{4\times 7-3x\times 9x}{63x}
Since \frac{4\times 7}{63x} and \frac{3x\times 9x}{63x} have the same denominator, subtract them by subtracting their numerators.
\frac{28-27x^{2}}{63x}
Do the multiplications in 4\times 7-3x\times 9x.
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}