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Câu 1:
A = \(\dfrac{-7}{12}+\dfrac{11}{8}-\dfrac{5}{9}=\dfrac{-42}{72}+\dfrac{99}{72}-\dfrac{40}{72}=\dfrac{-42+99-40}{72}=\dfrac{17}{72}\)
\(B=\dfrac{1}{7}-\dfrac{8}{7}:8-3:\dfrac{3}{4}.2^2=\dfrac{1}{7}-\dfrac{8}{7}.\dfrac{1}{8}-3.\dfrac{4}{3}.4=\dfrac{1}{7}-\dfrac{1}{7}-16=0-16=-16\)
\(C=1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):\dfrac{11}{5}=\dfrac{7}{5}.\dfrac{15}{49}-\dfrac{22}{15}.\dfrac{5}{11}=\dfrac{3}{7}-\dfrac{2}{3}=\dfrac{9-14}{21}=-\dfrac{5}{21}\)
Vậy A=\(\dfrac{17}{72};B=-16;C=\dfrac{-5}{21}\)
Câu 2:
a. \(\dfrac{-11x}{12}+\dfrac{3}{4}=-\dfrac{1}{6}\)
\(\Rightarrow\dfrac{-11x}{12}=-\dfrac{1}{6}-\dfrac{3}{4}\)
\(\Rightarrow\dfrac{-11x}{12}=\dfrac{-2}{12}-\dfrac{9}{12}\)
\(\Rightarrow\dfrac{-11x}{12}=\dfrac{-11}{12}\)
\(\Rightarrow-11x=\dfrac{-11.12}{12}\)
\(\Rightarrow-11x=-11\Rightarrow x=1\)
Vậy x=1
b. \(3-(\dfrac{1}{6}-x).\dfrac{2}{3}=\dfrac{2}{3}\Rightarrow3-\left(\dfrac{1}{6}-x\right)=1\)
\(\Rightarrow-(\dfrac{1}{6}-x)=1-3\Rightarrow\dfrac{1}{6}+x=-2\)
\(\Rightarrow x=2-\dfrac{1}{6}\Rightarrow x=\dfrac{11}{6}\)
Vậy x = \(\dfrac{11}{6}\)
Câu 4:
Ta có: \(\dfrac{1}{2.3}=\dfrac{1}{6}\)
\(\dfrac{1}{2}-\dfrac{1}{3}=\dfrac{3}{6}-\dfrac{2}{6}=\dfrac{1}{6}\)
\(\Rightarrow\dfrac{1}{2.3}=\dfrac{1}{2}-\dfrac{1}{3}\)
\(\dfrac{-7}{12}+\dfrac{11}{8}-\dfrac{5}{9}=\dfrac{-7}{12}+\dfrac{59}{72}=\dfrac{17}{72}\) \(\dfrac{1}{7}-\dfrac{8}{7}:8-3:\dfrac{3}{4}.\left(-2\right)^2=\dfrac{1}{7}-\dfrac{1}{7}-4.4=\left(-16\right)\) \(\dfrac{1}{4}.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):\dfrac{11}{5}=\dfrac{15}{49}-\dfrac{22}{15}:\dfrac{11}{5}=\dfrac{15}{49}-\dfrac{2}{3}=\dfrac{-53}{147}\)
Câu 1 :
a, 8.( -5 ).( -4 ).2
= [ 8.2 ].[( -5 ).(-4 ]
= 16.20
= 320
b, \(1\frac{3}{7}+\frac{-1}{3}+2\frac{4}{7}\)
\(=\frac{10}{7}+\frac{-1}{3}+\frac{18}{7}\)
\(=\frac{11}{3}\)
c, \(\frac{8}{5}.\frac{2}{3}+\frac{-5.5}{3.5}\)
\(=\frac{8}{3}+\frac{-5}{3}\)
\(=\frac{3}{3}=1\)
d, \(\frac{6}{7}+\frac{5}{8}:5-\frac{3}{16}.\left(-2\right)^2\)
\(=\frac{6}{7}+\frac{1}{8}-\frac{3}{16}.4\)
\(=\frac{55}{56}-\frac{3}{4}\)
\(=\frac{13}{56}\)
Câu 2 :
a, 2x + 10 = 16
2x = 16 + 10
2x = 26
x = 26 : 2
x = 13
b, \(x-\frac{1}{3}=\frac{5}{4}\)
\(x=\frac{5}{4}+\frac{1}{3}\)
\(x=\frac{19}{12}\)
c, \(2x+3\frac{1}{3}=7\frac{1}{3}\)
\(2x+\frac{10}{3}=\frac{22}{3}\)
\(2x=\frac{22}{3}-\frac{10}{3}\)
\(2x=4\)
\(x=4:2\)
\(x=2\)
d, \(\left(\frac{2}{11}+\frac{1}{3}\right)x=\left(\frac{1}{7}-\frac{1}{8}\right).56\)
\(\frac{17}{33}x=1\)
\(x=1-\frac{17}{33}\)
\(x=\frac{16}{33}\)
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: =7/8:(2/9-18+1/36)-5/12
=-7/142-5/12=-397/852
b: =3/7(4/9+5/9:6/12)=2/3
c: =5^8(16/31-47/31)+1/3=-5^8+1/3
d: =7/2(3/8+5/8:4/15)=609/64
dễ mk bn cho mình hỏi nhé câu 4 là \(\frac{1}{2\cdot3}\)hay là\(\frac{1}{2}\cdot3\)
Cau 1
A=17/72 B=16 C=-5/21
Cau 2
a) x=1 b) -10/3