Bài 17 trang 15 SGK Toán 6 tập 2

Đề bài

Rút gọn:

a)  \(\dfrac{3.5}{8.24}\) ;                   b) \(\dfrac{2.14}{7.8}\) 

c) \(\dfrac{3.7.11}{22.9}\) ;                d) \(\dfrac{8.5-8.2}{16}\) ;

e) \(\dfrac{11.4-11}{2-13}\) . 

Lời giải chi tiết

a) \(\dfrac{3.5}{8.24}=\dfrac{3.5:3}{8.24:3}=\dfrac{5}{8.8}=\dfrac{5}{64}\) .

b) \(\dfrac{2.14}{7.8}=\dfrac{2.2.7}{7.2.2.2}=\dfrac{1}{2};\)

c) \(\dfrac{3.7.11}{22.9}=\dfrac{3.7.11}{2.11.3.3}=\dfrac{7}{2.3}=\dfrac{7}{6};\)

d)  \(\dfrac{{8.5 - 8.2}}{{16}} = \dfrac{{8.(5 - 2)}}{{2.8}} = \dfrac{{8.3}}{{2.8}} = \dfrac{3}{2}\)

e) \(\dfrac{{11.4 - 11}}{{2 - 13}} = \dfrac{{11.4 - 11.1}}{{ - 11}}\)\(\, = \dfrac{{11.(4 - 1)}}{{ - 11}} = \dfrac{{11.3}}{{ - 11}} = \dfrac{3}{{ - 1}} =  - 3.\)

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