Đề bài

Rút gọn các phân số sau về phân số tối giản: a)     \(\frac{{12}}{{24}};\frac{{13}}{{39}};\frac{{35}}{{105}}\) b)    \(\frac{{120}}{{245}};\frac{{134}}{{402}};\frac{{213}}{{852}}\) c)     \(\frac{{234}}{{1170}};\frac{{1221}}{{3663}};\frac{{2133}}{{31995}}\)

Lời giải chi tiết

a)     Ta có:\(\frac{{12}}{{24}}=\frac{12:12}{24:12}=\frac{1}{2};\\\frac{{13}}{{39}}=\frac{13:13}{39:13}=\frac{1}{3};\\\frac{{35}}{{105}}=\frac{35:35}{105:35}=\frac{1}{3}.\)b)    Ta có:\(\begin{array}{l}\frac{{120}}{{245}} = \frac{{120:5}}{{245:5}} = \frac{{24}}{{49}};\\\frac{{134}}{{402}} = \frac{{134:134}}{{402:134}} = \frac{1}{3};\\\frac{{213}}{{852}} = \frac{{213:213}}{{852:213}} = \frac{1}{4}.\end{array}\)c)    Ta có:\(\begin{array}{l}\frac{{234}}{{1170}} = \frac{{234:234}}{{1170:234}} = \frac{1}{5};\\\frac{{1221}}{{3663}} = \frac{{1221:1221}}{{3663:1221}} = \frac{1}{3};\\\frac{{2133}}{{31995}} = \frac{{2133:2133}}{{31995:2133}} = \frac{1}{{15}}.\end{array}\)