Question

помогите пожалуйста ​

Answer 1

$\frac{16 {a}^{2} }{21 {b}^{4} } \div \frac{12 {a}^{3} }{7b {}^{6} } = \frac{16 {a}^{2} \times7b {}^{6} }{21{b}^{4} \times 12 {a}^{3} } = \frac{4 {b}^{2} }{3 \times 3a} = \frac{4b {}^{2} }{9a} \\ \frac{ {x}^{2} + 12x + 36}{ {x}^{2} - 81} \times \frac{2x + 18}{x + 6} = \frac{(x + 6) {}^{2} \times 2(x + 9)}{(x - 9)(x + 9)(x + 6)} = \frac{2(x + 6)}{x - 9} = \frac{2x + 12}{x - 9}$