Câu thứ 2 hình như bị sai đề
1998 sửa thành 1989
\(\frac{121.75.130.169}{39.60.11.198}\\ =\frac{11.11.5.15.13.10.13.13}{13.3.15.4.11.11.18}\)
\(=\frac{5.10.13.13}{3.4.18}\)
\(=\frac{4225}{108}\)
Câu 1
121×75×130×19/39×60×11×198
=11×11×15×5×130×13×13/13×13×15×4×11×11×18
=5×130/4×18=650/72325/36
Câu 2
1998×1990+3978/1992×1991-3984
=3976020/3962088=> 994005/990522
\(\frac{1989.1990+3978}{1992.1991-3984}\)
\(=\frac{1989.1990+1989.2}{1992.1991-1992.2}\)
\(=\frac{1989.\left(1990+2\right)}{1992.\left(1991-2\right)}\)
\(=\frac{1989.1992}{1992.1989}\)
\(=1\)
HOK TỐT
1)121.75.130.169/39.60.11.198
=11.11.3.25.13.10.169/13.3.6.10.11.11.18
=25.169/6.18=4225/108
2)1989.1990+3978/1992.1991-3984
=1989.1990+1989.2/1992.1991-1992.2
=1989.(1990+2)/1992.(1991-2)
=1989.1992/1992.1989=1