Đề bài

Rút gọn rồi quy đồng mẫu các phân số sau: \(\begin{array}{l}a)\frac{{29 - 5}}{{54}}; \frac{{45 - 54}}{{33}};\\b)\frac{{18 + 14}}{{18}}; \frac{{26 - 50}}{{30}}\end{array}\)

Lời giải chi tiết

\(\begin{array}{l}a)\frac{{29 - 5}}{{54}} = \frac{{24}}{{54}} = \frac{{24:6}}{{54:6}} = \frac{4}{9};\\\frac{{45 - 54}}{{33}} = \frac{{ - 9}}{{33}} = \frac{{( - 9):3}}{{33:3}} = \frac{{ - 3}}{{11}}\end{array}\).Ta được\(\frac{4}{9} = \frac{{4.11}}{{9.11}} = \frac{{44}}{{99}};\frac{{ - 3}}{{11}} = \frac{{( - 3).9}}{{11.9}} = \frac{{ - 27}}{{99}}\)\(\begin{array}{l}b)\frac{{18 + 14}}{{18}} = \frac{{32}}{{18}} = \frac{{32:2}}{{18:2}} = \frac{{16}}{9};\\\frac{{26 - 50}}{{30}} = \frac{{ - 24}}{{30}} = \frac{{( - 24):6}}{{30:6}} = \frac{{ - 4}}{5}\end{array}\).Ta được\(\frac{{16}}{9} = \frac{{16.5}}{{9.5}} = \frac{{80}}{{45}};\frac{{ - 4}}{5} = \frac{{( - 4).9}}{{5.9}} = \frac{{ - 36}}{{45}}\)