Question

Bài 1:Rút gọn phân số

a)\(\frac{-2019\cdot2018+1}{\left(-2017\right)\cdot\left(-2019\right)+2018}\)

b)\(\frac{6\cdot9-2\cdot7}{63\cdot3-119}\)

c)\(\frac{2929-101}{2\cdot1919+404}\)

d)\(\frac{2\cdot3+4\cdot6+14\cdot21}{3\cdot5+6\cdot10+21\cdot35}\)

Answer 1

d)\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}=\frac{2.3+2.2.6+2.7.21}{3.5+3.2.10+3.7.35}=\frac{2.3+2.12+2.147}{3.5+3.20+3.245}=\frac{2\left(3+12+147\right)}{3\left(5+20+245\right)}\)

\(=\frac{2.162}{3.270}=\frac{54}{135}=\frac{2}{5}\)

Answer 2

\(a.\frac{-2019.2018+1}{\left(-2017\right).\left(-2019\right)+2018}\)

\(=\frac{2019.\left(-2018\right)+1}{2019.2017+2018}\)

\(=\frac{2019.\left(-2018\right)+1}{2019.2018-1}\)

\(=-\frac{2018}{2018}\)

\(=-1\)

Answer 3

c)\(\frac{2929-101}{2.1919+404}=\frac{29.101-101}{29.101+101.4}=\frac{101\left(29-1\right)}{101\left(29+4\right)}=\frac{28}{33}\)

Answer 4

\(b.\frac{6.9-2.7}{63.3-119}\)

\(=\frac{6.9-2.7}{21.9-17.7}\)

\(=\frac{6-2}{21-17}\)

\(=\frac{4}{4}\)

\(=1\)

Answer 5

\(\frac{6.9-2.7}{63.3-11.9}=\frac{2.3.9-2.7}{9.7.3-9.11}=\frac{2.27-2.7}{9.21-9.11}=\frac{2\left(27-7\right)}{9\left(21-11\right)}=\frac{2.20}{9.10}=\frac{4}{9}\)

(câu này hình như đề sai nên mình sửa nha)