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2: \(=\dfrac{-2}{75}+\dfrac{5}{39}=\dfrac{33}{325}\)
3: \(=\dfrac{6}{11}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{6}{11}\)
4: \(=\dfrac{7}{19}\left(\dfrac{5}{13}+\dfrac{8}{13}-1\right)=-2\cdot\dfrac{7}{19}=-\dfrac{14}{19}\)
5: \(=\dfrac{2}{7}\left(\dfrac{4}{23}-\dfrac{27}{23}+1\right)=0\)
6: \(=\dfrac{3}{8}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\dfrac{11}{8}=\dfrac{3}{8}+\dfrac{11}{8}=\dfrac{14}{8}=\dfrac{7}{4}\)
Bài 1:
a: \(x=\dfrac{2}{3}:\dfrac{3}{5}=\dfrac{2}{3}\cdot\dfrac{5}{3}=\dfrac{10}{9}\)
b: \(x=\dfrac{17}{8}:\dfrac{7}{17}=\dfrac{17}{8}\cdot\dfrac{17}{7}=\dfrac{289}{56}\)
c: \(x=-\dfrac{3}{4}:\dfrac{7}{12}=\dfrac{-3}{4}\cdot\dfrac{12}{7}=\dfrac{-63}{28}=-\dfrac{9}{4}\)
d: \(\Leftrightarrow x\cdot\dfrac{1}{6}=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{1}{4}\)
hay \(x=\dfrac{1}{4}:\dfrac{1}{6}=\dfrac{3}{2}\)
e: \(\Leftrightarrow\dfrac{1}{2}:x=-4-\dfrac{1}{3}=-\dfrac{17}{3}\)
hay \(x=-\dfrac{1}{2}:\dfrac{17}{3}=\dfrac{-3}{34}\)
a: \(\Leftrightarrow\left(\dfrac{13}{4}:x\right)\cdot\left(-\dfrac{5}{4}\right)=\dfrac{-10}{6}-\dfrac{5}{6}=\dfrac{-15}{6}=\dfrac{-5}{2}\)
\(\Leftrightarrow\dfrac{13}{4}:x=\dfrac{5}{2}\cdot\dfrac{5}{4}=\dfrac{25}{8}\)
hay \(x=\dfrac{13}{4}:\dfrac{25}{8}=\dfrac{13}{4}\cdot\dfrac{8}{25}=\dfrac{26}{25}\)
b: \(\Leftrightarrow\dfrac{3}{4}:x=\dfrac{11}{36}-\dfrac{1}{4}=\dfrac{2}{36}=\dfrac{1}{18}\)
=>\(x=\dfrac{3}{4}:\dfrac{1}{18}=\dfrac{54}{4}=\dfrac{27}{2}\)
c: \(\Leftrightarrow\left(-\dfrac{6}{5}+x\right):\left(-3.6\right)=-\dfrac{7}{4}+\dfrac{1}{4}\cdot8=\dfrac{1}{4}\)
=>x-6/5=-9/10
=>x=3/10
\(\frac{2}{5}\cdot\frac{1}{2}-\frac{2}{5}\cdot\frac{1}{3}-\frac{2}{5}\cdot\frac{1}{6}\)
\(=\frac{2}{5}\cdot\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
\(=\frac{2}{5}\cdot0=0\)
\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)\)
\(=\frac{19+3}{11}+\frac{8}{13}\)
\(=2+\frac{8}{13}=\frac{34}{13}\)
\(1,5+2\frac{3}{5}+\frac{4}{7}\)
\(=\frac{3}{2}+\frac{13}{5}+\frac{4}{7}\)
\(=\frac{327}{70}\)
\(x-\frac{5}{4}=6\cdot\frac{5}{8}\)
\(x-\frac{5}{4}=\frac{15}{4}\)
\(x=\frac{15}{4}+\frac{5}{4}\)
\(x=\frac{15+5}{4}=\frac{20}{4}=5\)
\(x\div2\frac{3}{4}=5\frac{2}{3}\)
\(x=5\frac{2}{3}\cdot2\frac{3}{4}\)
\(x=\frac{187}{12}\)
\(\frac{2}{3}\div x=\frac{3}{4}\)
\(x=\frac{2}{3}\div\frac{3}{4}\)
\(x=\frac{8}{9}\)
0, 75 = 3/4
Hiệu số phần bằng nhau là:
4 - 3 = 1
Số bé là:
0, 75 : 1 x 3 = 2, 25
Số lớn là:
2, 25 + 0, 75 = 3
Đ/s: ...
Trung bình cộng của 3 số là:
6045 : 3 = 2015
=> Số thứ 2 là 2015
Số thứ nhất là:
2015 - 1 = 2014
Số thứ 3 là:
2015 + 1 = 2016
Đ/s: ...
x - 5/4 = 6 . 5/8
x - 5/4 = 15/4
x = 15/4 + 5/4
x = 5