Bài 7: Tỉ lệ thức

IY

Bài 1:Tìm x

a, \(\dfrac{x}{6}=\dfrac{7}{3}\)

b,\(\dfrac{20}{x}=\dfrac{-12}{15}\)

c,\(\dfrac{-15}{35}=\dfrac{27}{x}\)

d,\(\dfrac{\dfrac{4}{5}}{1\dfrac{2}{5}}=\dfrac{2\dfrac{2}{5}}{x}\)

e,\(\dfrac{x}{1\dfrac{1}{4}}=\dfrac{1\dfrac{1}{5}}{2}\)

f,\(\dfrac{\dfrac{1}{2}}{1\dfrac{1}{4}}=\dfrac{x}{3\dfrac{1}{3}}\)

Bài 2:Tìm x

a,\(3x:2,7=\dfrac{1}{3}:2\dfrac{1}{4}\)

b,\(3:0,4x=1:0,01\)

c,\(4,5:0,3=2,25:0,1x\)

d,\(x:27=-2:3,6\)

Bài 3:Tìm x

a,\(1,35:0,2=1,25:0,1x\)

b,\(3,8:2x=\dfrac{1}{4}:2\dfrac{2}{3}\)

c,\(3\dfrac{1}{3}:2,4=0,35x:0,35\)

d,\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:0,1x\)

GIÚP MÌNH VỚI NHAkhocroi

NH
30 tháng 7 2017 lúc 21:58

\(a,\dfrac{x}{6}=\dfrac{7}{3}\Rightarrow x=\dfrac{6.7}{3}\Rightarrow x=14\)

\(b,\dfrac{20}{x}=\dfrac{-12}{15}\Rightarrow x=\dfrac{20.15}{-12}\Rightarrow x=-25\)

\(c,\dfrac{-15}{35}=\dfrac{27}{x}\Rightarrow x=\dfrac{35.27}{-15}\Rightarrow x=-63\)

\(d,\dfrac{\dfrac{4}{5}}{1\dfrac{2}{5}}=\dfrac{2\dfrac{2}{5}}{x}\Rightarrow\dfrac{\dfrac{4}{5}}{\dfrac{7}{5}}=\dfrac{\dfrac{12}{5}}{x}\Rightarrow x=\dfrac{\dfrac{7}{5}.\dfrac{12}{5}}{\dfrac{4}{5}}\Rightarrow x=\dfrac{\dfrac{84}{25}}{\dfrac{4}{5}}\Rightarrow x=\dfrac{21}{5}\)

\(e,\dfrac{x}{1\dfrac{1}{4}}=\dfrac{5}{2}\Rightarrow\dfrac{x}{\dfrac{5}{4}}=\dfrac{5}{2}\Rightarrow x=\dfrac{5}{2}.\dfrac{5}{4}\Rightarrow x=\dfrac{25}{8}\)

\(f,\dfrac{\dfrac{1}{2}}{1\dfrac{1}{4}}=\dfrac{x}{3\dfrac{1}{3}}\Rightarrow\dfrac{\dfrac{1}{2}}{\dfrac{5}{4}}=\dfrac{x}{\dfrac{10}{3}}\Rightarrow x=\dfrac{\dfrac{10}{3}.\dfrac{1}{2}}{\dfrac{5}{4}}\Rightarrow x=\dfrac{\dfrac{5}{3}}{\dfrac{5}{4}}\Rightarrow x=\dfrac{4}{3}\)

Bình luận (0)
NH
31 tháng 7 2017 lúc 10:16

a,\(1.25:0.2=1.25:0.1x\Rightarrow1.25:0.1x=\dfrac{25}{4}\Rightarrow0.1x=\dfrac{1}{5}\Rightarrow x=2\)

b,\(3.8:2x=\dfrac{1}{4}:2\dfrac{2}{3}\Rightarrow3.8:2x=\dfrac{3}{32}\Rightarrow2x=\dfrac{608}{15}\Rightarrow x=\dfrac{304}{15}\)

Bình luận (2)
NH
31 tháng 7 2017 lúc 10:10

\(a,3x:2,7=\dfrac{1}{3}:2\dfrac{1}{4}\Rightarrow3x:2,7=\dfrac{4}{27}\Rightarrow3x=\dfrac{2}{5}\Rightarrow x=\dfrac{2}{15}\)

b,\(3:0.4x=1:0.01\Rightarrow3:0.4x=100\Rightarrow0.4x=\dfrac{3}{100}\Rightarrow x=\dfrac{3}{40}\)

c,

\(4,5:0,3=2,25:0.1x\Rightarrow2.25:0.1x=15\Rightarrow0.1x=\dfrac{3}{20}\Rightarrow x=\dfrac{3}{2}\)

d,\(x:27=-2:3,6\Rightarrow x:27=\dfrac{-5}{9}\Rightarrow x=-15\)

Bình luận (0)

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