Evaluate
-\frac{2\left(a^{2}-4\right)}{a^{2}+4}
Expand
-\frac{2\left(a^{2}-4\right)}{a^{2}+4}
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\frac{2-2\times \frac{a^{2}}{2^{2}}}{1+\left(\frac{a}{2}\right)^{2}}
To raise \frac{a}{2} to a power, raise both numerator and denominator to the power and then divide.
\frac{2-\frac{2a^{2}}{2^{2}}}{1+\left(\frac{a}{2}\right)^{2}}
Express 2\times \frac{a^{2}}{2^{2}} as a single fraction.
\frac{2-\frac{a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
Cancel out 2 in both numerator and denominator.
\frac{\frac{2\times 2}{2}-\frac{a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
To add or subtract expressions, expand them to make their denominators the same. Multiply 2 times \frac{2}{2}.
\frac{\frac{2\times 2-a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
Since \frac{2\times 2}{2} and \frac{a^{2}}{2} have the same denominator, subtract them by subtracting their numerators.
\frac{\frac{4-a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
Do the multiplications in 2\times 2-a^{2}.
\frac{\frac{4-a^{2}}{2}}{1+\frac{a^{2}}{2^{2}}}
To raise \frac{a}{2} to a power, raise both numerator and denominator to the power and then divide.
\frac{\frac{4-a^{2}}{2}}{\frac{2^{2}}{2^{2}}+\frac{a^{2}}{2^{2}}}
To add or subtract expressions, expand them to make their denominators the same. Multiply 1 times \frac{2^{2}}{2^{2}}.
\frac{\frac{4-a^{2}}{2}}{\frac{2^{2}+a^{2}}{2^{2}}}
Since \frac{2^{2}}{2^{2}} and \frac{a^{2}}{2^{2}} have the same denominator, add them by adding their numerators.
\frac{\frac{4-a^{2}}{2}}{\frac{4+a^{2}}{2^{2}}}
Combine like terms in 2^{2}+a^{2}.
\frac{\left(4-a^{2}\right)\times 2^{2}}{2\left(4+a^{2}\right)}
Divide \frac{4-a^{2}}{2} by \frac{4+a^{2}}{2^{2}} by multiplying \frac{4-a^{2}}{2} by the reciprocal of \frac{4+a^{2}}{2^{2}}.
\frac{2\left(-a^{2}+4\right)}{a^{2}+4}
Cancel out 2 in both numerator and denominator.
\frac{-2a^{2}+8}{a^{2}+4}
Use the distributive property to multiply 2 by -a^{2}+4.
\frac{2-2\times \frac{a^{2}}{2^{2}}}{1+\left(\frac{a}{2}\right)^{2}}
To raise \frac{a}{2} to a power, raise both numerator and denominator to the power and then divide.
\frac{2-\frac{2a^{2}}{2^{2}}}{1+\left(\frac{a}{2}\right)^{2}}
Express 2\times \frac{a^{2}}{2^{2}} as a single fraction.
\frac{2-\frac{a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
Cancel out 2 in both numerator and denominator.
\frac{\frac{2\times 2}{2}-\frac{a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
To add or subtract expressions, expand them to make their denominators the same. Multiply 2 times \frac{2}{2}.
\frac{\frac{2\times 2-a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
Since \frac{2\times 2}{2} and \frac{a^{2}}{2} have the same denominator, subtract them by subtracting their numerators.
\frac{\frac{4-a^{2}}{2}}{1+\left(\frac{a}{2}\right)^{2}}
Do the multiplications in 2\times 2-a^{2}.
\frac{\frac{4-a^{2}}{2}}{1+\frac{a^{2}}{2^{2}}}
To raise \frac{a}{2} to a power, raise both numerator and denominator to the power and then divide.
\frac{\frac{4-a^{2}}{2}}{\frac{2^{2}}{2^{2}}+\frac{a^{2}}{2^{2}}}
To add or subtract expressions, expand them to make their denominators the same. Multiply 1 times \frac{2^{2}}{2^{2}}.
\frac{\frac{4-a^{2}}{2}}{\frac{2^{2}+a^{2}}{2^{2}}}
Since \frac{2^{2}}{2^{2}} and \frac{a^{2}}{2^{2}} have the same denominator, add them by adding their numerators.
\frac{\frac{4-a^{2}}{2}}{\frac{4+a^{2}}{2^{2}}}
Combine like terms in 2^{2}+a^{2}.
\frac{\left(4-a^{2}\right)\times 2^{2}}{2\left(4+a^{2}\right)}
Divide \frac{4-a^{2}}{2} by \frac{4+a^{2}}{2^{2}} by multiplying \frac{4-a^{2}}{2} by the reciprocal of \frac{4+a^{2}}{2^{2}}.
\frac{2\left(-a^{2}+4\right)}{a^{2}+4}
Cancel out 2 in both numerator and denominator.
\frac{-2a^{2}+8}{a^{2}+4}
Use the distributive property to multiply 2 by -a^{2}+4.
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}