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\(a,\frac{-7}{25}.\frac{11}{13}+\frac{-7}{25}.\frac{2}{13}-\frac{18}{25}\)
\(=\frac{-7}{25}.\left(\frac{11}{13}+\frac{2}{13}\right)-\frac{18}{25}=\frac{-7}{25}-\frac{18}{25}=-1\)
\(b,\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{12}=\frac{5}{7}.\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{12}\right)=\frac{5}{7}.\left(\frac{4}{12}-\frac{3}{12}-\frac{1}{12}\right)\)
\(=\frac{5}{7}.0=0\)
c)\(5\frac{2}{5}.4\frac{2}{7}+5\frac{5}{7}.5\frac{2}{5}=\frac{27}{5}.\frac{30}{7}+\frac{40}{7}.\frac{27}{5}=\frac{27}{5}.\left(\frac{30}{7}+\frac{40}{7}\right)\)
\(=\frac{27}{5}.10=27.2=54\)
\(d,75\%-1\frac{1}{2}+0,5:\frac{5}{12}-\left(\frac{-1}{2}\right)^2=\frac{3}{4}-\frac{3}{2}+\frac{1}{2}.\frac{12}{5}-\frac{1}{4}\)
\(=\left(\frac{3}{4}-\frac{1}{4}\right)-\frac{3}{2}+\frac{6}{5}=\frac{1}{2}-\frac{3}{2}+\frac{6}{5}=-1+\frac{6}{5}=\frac{-5}{5}+\frac{6}{5}=\frac{1}{5}\)
\(\frac{5}{7}\times\frac{1}{3}-\frac{5}{7}\times\frac{1}{4}-\frac{5}{7}\times\frac{1}{2}\)
\(=\frac{5}{7}\times\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{2}\right)\)
\(=\frac{5}{7}\times\left(\frac{4}{12}-\frac{3}{12}-\frac{6}{12}\right)\)
\(=\frac{5}{7}\times\left(\frac{4-3-6}{12}\right)\)
\(=\frac{5}{7}\times\frac{-5}{12}\)
\(=\frac{5\times\left(-5\right)}{7\times12}\)
\(=\frac{-25}{84}\)
\(\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{2}\)
= \(\frac{5}{7}.\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{2}\right).1\)
\(=\frac{5}{7}.\frac{-5}{12}\)
\(=-\frac{25}{84}\)
a) -7/25 . 11/13 + -7/25 . 2/13 - 18/25=-1
b) 5/7 . 1/3 - 5/7 . 1/4 - 5/7 . 1/12=0
c) 5 + 2/5 . 4+ 2/7 + 5 + 5/7 . 5+ 2/5=18
d) 75% - 3/2 + 0,5 - [ -1/2]^2=-1/2
Bài 6:
a: \(x=-\dfrac{2}{3}-\dfrac{1}{7}=\dfrac{-14-3}{21}=\dfrac{-17}{21}\)
d: \(x=\dfrac{9}{10}\cdot\dfrac{-5}{9}=\dfrac{-1}{2}\)
e: \(\Leftrightarrow x\cdot\dfrac{1}{3}=\dfrac{14}{21}-\dfrac{3}{21}=\dfrac{11}{21}\)
=>x=11/7
\(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\\ =\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}\\ =\dfrac{1}{2}+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)+\dfrac{4}{5}\\ =\dfrac{1}{2}+0+\dfrac{4}{5}\\ =\dfrac{1}{2}+\dfrac{4}{5}\\ =\dfrac{5}{10}+\dfrac{8}{10}\\ =\dfrac{13}{10}\)
\(\dfrac{-3}{7}+\dfrac{3}{4}:\dfrac{3}{14}\\ =\dfrac{-3}{7}+\dfrac{3}{4}\cdot\dfrac{14}{3}\\ =\dfrac{-3}{7}+\dfrac{7}{2}\\ =\dfrac{-6}{14}+\dfrac{49}{14}\\ =\dfrac{43}{14}\)
a,3/7 +1/2-[-3]/70
=13/14 -[-3]/70
=65/70 -[-3]/70
=34/35
b,3/5+-1/25 -35/100
=14/25 - 35/100
=56 /100 -35/100
= 21/100
c ,5/12 -3/-16+3/4
=29/48 +3/4
= 29/48 +36/48
=65/48
d, 5/15 +4/-12 +1/7 -1/-6
= 1/3 +1/-3 +1/7-1/-6
=0+1/7-1/-6
= 13/42
A.\(\dfrac{3}{7}+\dfrac{1}{2}+\dfrac{\left(-3\right)}{70}\)
=\([\dfrac{30}{70}+\dfrac{\left(-3\right)}{70}]\)+\(\dfrac{1}{2}\)
= \(\dfrac{27}{70}+\dfrac{35}{70}\)
=\(\dfrac{62}{70}=\dfrac{31}{35}\)
B.\(\dfrac{3}{5}+\dfrac{-1}{25}-\dfrac{35}{100}\)
=\(\dfrac{60}{100}+\dfrac{-4}{100}-\dfrac{35}{100}\)
=\(\dfrac{60+\left(-4\right)-35}{100}\)
=\(\dfrac{21}{100}\)
C.\(\dfrac{5}{12}-\dfrac{3}{-16}+\dfrac{3}{4}\)
=\(\left(\dfrac{5}{12}+\dfrac{9}{12}\right)-\dfrac{-3}{16}\)
=\(\dfrac{7}{6}-\dfrac{-3}{16}\)
=\(\dfrac{56}{48}-\dfrac{-9}{48}\)=\(\dfrac{65}{48}\)
D.\(\dfrac{5}{15}+\dfrac{4}{-12}+\dfrac{1}{7}-\dfrac{1}{-6}\)
=\(\dfrac{1}{3}+\dfrac{1}{7}+(\dfrac{-2}{6}-\dfrac{-1}{6})\)
=\(\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{-1}{6}\)
=\((\dfrac{1}{3}+\dfrac{-1}{6})+\dfrac{1}{7}\)
=\(\dfrac{1}{6}+\dfrac{1}{7}\)=\(\dfrac{13}{42}\)