Question

помогите пожалуйста ​

Answer 1

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