7,5 - { 3 phần 1 phần 5 + 2,5
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T
18 tháng 7 2018
a)\(\dfrac{2,5}{7,5}=\dfrac{x}{\dfrac{3}{5}}\)
<=>\(x=\dfrac{2,5.\dfrac{3}{5}}{7,5}\)
<=>\(x=\dfrac{1,5}{7,5}=\dfrac{1}{5}=0,2\)
b)\(\dfrac{2\dfrac{2}{3}}{x}=\dfrac{1\dfrac{17}{9}}{2}\)
<=>\(\dfrac{\dfrac{8}{3}}{x}=\)\(\dfrac{\dfrac{26}{9}}{2}\)
<=>\(\dfrac{\dfrac{8}{3}.2}{\dfrac{26}{9}}=\dfrac{24}{13}\)
c)\(\dfrac{x-1}{1,5}=\dfrac{2,8}{0,5}\)
<=>\(x-1=\dfrac{1,5.2,8}{0,5}\)
<=>\(x-1=\dfrac{42}{5}=8,4\)
d)\(\dfrac{0,6}{x}=\dfrac{x}{2,4}\)
<=>\(x^2=0,6.2,4 \)
<=>\(x^2=\dfrac{36}{25}\)
<=>\(x=\sqrt{\dfrac{36}{25}}=\dfrac{6}{5}=1,2\)
ND
0
UT
16 tháng 4 2021
\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)
\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)
\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)
\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)
bài 2
\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)
b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)
16 tháng 4 2021
Bài 1:
a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)
\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)
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