Đề bài

Thực hiện các phép nhân phân thức sau: a) \(\frac{3}{{5a}}.\frac{{2b}}{5}\)     b) \(\frac{{2a}}{3}.\frac{6}{{4b}}\) c) \(\frac{{{a^2}}}{{15}}.\frac{5}{a}\) d) \(\frac{{18}}{{{a^3}}}.\frac{{{a^2}}}{{30a}}\)

Lời giải chi tiết

a) \(\frac{3}{{5a}}.\frac{{2b}}{5} = \frac{{3.2b}}{{5a.5}} = \frac{{6b}}{{25a}}\)  b) \(\frac{{2a}}{3}.\frac{6}{{4b}} = \frac{{2a.6}}{{3.4b}} = \frac{{2a.3.2}}{{3.2.2b}} = \frac{a}{b}\)c) \(\frac{{{a^2}}}{{15}}.\frac{5}{a} = \frac{{a.a.5}}{{3.5.a}} = \frac{a}{3}\)d) \(\frac{{18}}{{{a^3}}}.\frac{{{a^2}}}{{30a}} = \frac{{6.3.{a^2}}}{{{a^2}.a.6.5a}} = \frac{3}{{5{a^2}}}\)