Question

7 класс 2 примера помогите прошу

Answer 1

1) $frac{b-3}{8 b^{4} } * frac{3b}{ b^{2} -9} = frac{(b-3)*3b}{8 b^{4}(b-3)(b+3) } = frac{3}{8 b^{3}(b+3) }= \ =frac{3}{8 b^{4}+24 b^{3} }$
2) $frac{4-b}{ b^{2}-6b+9 } * frac{3b-9}{ b^{2}-16 } = frac{-(b-4)*3(b-3)}{(b-3)^{2} *(b-4)(b+4)} = \ frac{-3}{(b-3)(b+4)} =frac{3}{(3-b)(b+4)} = frac{3}{- b^{2}-b+12 }$