Solve a^2-81/7a+63/frac{9-a{7}}

$$\frac{ \frac{ { a }^{ 2 } -81 }{ 7a+63 } }{ \frac{ 9-a }{ 7 } }$$

Evaluate

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Short Solution Steps

Divide \frac{a^{2}-81}{7a+63} by \frac{9-a}{7} by multiplying \frac{a^{2}-81}{7a+63} by the reciprocal of \frac{9-a}{7}.

$$\frac{\left(a^{2}-81\right)\times 7}{\left(7a+63\right)\left(9-a\right)}$$

Factor the expressions that are not already factored.

$$\frac{7\left(a-9\right)\left(a+9\right)}{7\left(a+9\right)\left(-a+9\right)}$$

Extract the negative sign in -9+a.

$$\frac{-7\left(a+9\right)\left(-a+9\right)}{7\left(a+9\right)\left(-a+9\right)}$$

Cancel out 7\left(a+9\right)\left(-a+9\right) in both numerator and denominator.

$$-1$$

Factor

$$-1$$