Question

$frac{3b}{a^2-81b^2}/frac{b}{a^2-9ab}$

Answer 1

=$frac{3b}{ a^{2} -81 b^{2} } * frac{ a^{2}-9ab }{b}= frac{3ba(a-9b)}{b(a-9b)(a+9b)} = frac{3a}{a+9b}$

Answer 2

Спасибо)

Answer 3

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Answer 4

$frac{3b}{a^2-81b^2}:frac{b}{a^2-9ab}=frac{3b}{(a-9b)(a+9b)}cdot frac{a(a-9b)}{b}=\ =frac{3a}{a+9b}$