Question

Спростіть вираз:6а/а-7-21/а+7+6а^2/49-а^2

Answer 1

Объяснение:

$\frac{6a}{a - 7} - \frac{21}{a + 7} + \frac{6a {}^{2} }{49 - a {}^{2} } =\frac{6a\left(a+7\right)}{\left(a-7\right)\left(a+7\right)}-\frac{21\left(a-7\right)}{\left(a-7\right)\left(a+7\right)}+\frac{6a^{2}}{49-a^{2}} =\frac{6a\left(a+7\right)-21\left(a-7\right)}{\left(a-7\right)\left(a+7\right)}+\frac{6a^{2}}{49-a^{2}} =\frac{6a^{2}+42a-21a+147}{\left(a-7\right)\left(a+7\right)}+\frac{6a^{2}}{49-a^{2}} =\frac{21a+147+6a^{2}}{\left(a-7\right)\left(a+7\right)}+\frac{6a^{2}}{49-a^{2}} =\frac{21a+147+6a^{2}}{\left(a-7\right)\left(a+7\right)}+\frac{6a^{2}}{\left(a-7\right)\left(-a-7\right)} =\frac{21a+147+6a^{2}}{\left(a-7\right)\left(a+7\right)}+\frac{-6a^{2}}{\left(a-7\right)\left(a+7\right)} =\frac{21a+147+6a^{2}-6a^{2}}{\left(a-7\right)\left(a+7\right)} =\frac{21a+147}{\left(a-7\right)\left(a+7\right)} =\frac{21\left(a+7\right)}{\left(a-7\right)\left(a+7\right)} =\frac{21}{a-7}$