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\(\left(\dfrac{1}{15}+\dfrac{1}{35}+\dfrac{1}{63}\right)x=1\)
\(\Leftrightarrow\dfrac{1}{9}x=1\)
\(\Leftrightarrow x=1:\dfrac{1}{9}\)
\(\Leftrightarrow x=9\)
=>1/2(2/15+2/35+2/63)*x=1
=>1/2(1/3-1/5+1/5-1/7+1/7-1/9)*x=1
=>1/2*2/9*x=1
=>x*1/9=1
=>x=9
a) \(x:3\frac{5}{6}=2\frac{8}{15}\) b) \(\frac{12}{5}:x+\frac{4}{3}=3\frac{2}{3}\)
\(x:\frac{23}{6}=\frac{38}{15}\) \(\frac{12}{5}:x+\frac{4}{3}=\frac{11}{3}\)
\(x=\frac{38}{15}\times\frac{23}{6}\) \(\frac{12}{5}:x=\frac{11}{3}-\frac{4}{3}\)
\(x=\frac{437}{45}\) \(\frac{12}{5}:x=\frac{7}{3}\)
\(x=\frac{12}{5}:\frac{7}{3}\)
\(x=\frac{36}{35}\)
1. a
\(\dfrac{8}{5}-\dfrac{5}{6}\cdot\dfrac{3}{4}\)
\(=\dfrac{8}{5}-\dfrac{5\cdot3}{3\cdot2\cdot4}\)
\(=\dfrac{8}{5}-\dfrac{5}{8}=\dfrac{39}{40}\)
1.b
\(=\dfrac{7}{8}+\dfrac{5}{6}\cdot\dfrac{3}{2}\)
\(=\dfrac{7}{8}+\dfrac{5\cdot3}{3\cdot2\cdot2}\)
\(=\dfrac{7}{8}+\dfrac{5}{4}=\dfrac{17}{8}\)
2.a
\(\dfrac{4}{5}+x=\dfrac{11}{10}\)
\(x=\dfrac{11}{10}-\dfrac{4}{5}=\dfrac{3}{10}\)
2.b
\(x-\dfrac{3}{4}=\dfrac{5}{7}\)
\(x=\dfrac{5}{7}+\dfrac{3}{4}=\dfrac{41}{28}\)
a, \(x:3\dfrac{5}{6}=2\dfrac{8}{15}\)
\(x:\dfrac{23}{6}\) = \(\dfrac{38}{15}\)
\(x=\dfrac{38}{15}\times\dfrac{23}{6}\)
\(x=\dfrac{437}{45}\)
b, \(\dfrac{12}{15}:x+\dfrac{4}{3}=3\dfrac{2}{3}\)
\(\dfrac{12}{15}:x+\dfrac{4}{3}=\dfrac{11}{3}\)
\(\dfrac{12}{15}:x=\dfrac{11}{3}-\dfrac{4}{3}\)
\(\dfrac{12}{15}:x=\dfrac{7}{3}\)
x= \(\dfrac{12}{15}:\dfrac{7}{3}=\dfrac{12}{35}\)
\(c)x:\dfrac{5}{4}=\dfrac{9}{5}+\dfrac{1}{2}\)
\(x:\dfrac{5}{4}=\dfrac{23}{10}\)
\(x=\dfrac{23}{10}\times\dfrac{5}{4}\)
\(x=\dfrac{23}{8}\)
\(\frac{1}{3}\cdot\frac{1}{x}+\left(\frac{1}{x}+1\right)\cdot\frac{2}{5}=\frac{9}{5}\)
ĐKXĐ \(x\ne0\)
\(\frac{1.1}{3x}+\left(\frac{1}{x}+\frac{x}{x}\right)\cdot\frac{2}{5}=\frac{9}{5}\)
\(\frac{1}{3x}+\frac{1+x}{x}\cdot\frac{2}{5}=\frac{9}{5}\)
\(\frac{1}{3x}+\frac{2\left(1+x\right)}{5x}=\frac{9}{5}\)
\(\frac{1}{3x}+\frac{2x+2}{5x}=\frac{9}{5}\)
\(\frac{5}{15x}+\frac{3\left(2x+2\right)}{5x}=\frac{9}{5}\)
\(\frac{5}{15x}+\frac{6x+6}{15x}=\frac{9}{5}\)
\(\frac{5+6x+6}{15x}=\frac{3x.9}{15x}\)
\(\frac{11+6x}{15x}=\frac{27x}{15x}\)
\(\Rightarrow11+6x=27x\)
\(\Rightarrow11=27x-6x\)
\(\Rightarrow11=21x\)
\(\Rightarrow x=\frac{11}{21}\)
Vậy \(S=\left\{\frac{11}{21}\right\}\)
P/s hình như mik lm dạng này r ?!?
x/3 = 14/21
<=> X x 21 = 3 x 14
X x 21 = 42
x = 42 : 21
x = 2
8/40 = 1/x
<=> 8 x X = 40 x 1
8 x X = 40
X = 40 : 8
X = 5
a, 2015 - 2 × X = 101
2 x X = 2015 - 101
2 x X = 1914
X = 1914 : 2
X = 957
1a. 2015 - 2 x X = 101
2 x X = 2015 - 101
X = 1914 : 2
X = 957
b. 7 - (11 + X - 13) : \(2\frac{2}{3}\)= 2
(11 + X - 13) : \(2\frac{2}{3}\) = 7 - 2
11 + X - 13 = 5 x \(2\frac{2}{3}\)
11 + X = \(\frac{40}{3}\)+ 13
X = \(\frac{79}{3}\)- 11
X = \(\frac{46}{3}\)
c. 2012 - 5 x X = 17
5 x X = 2012 - 17
X = 1995 : 5
X = 399
d. \(5\frac{3}{4}\)+ (X - 2) x \(\frac{1}{3}\)= \(17\frac{3}{4}\)
(X - 2) x \(\frac{1}{3}\) = \(17\frac{3}{4}\)- \(5\frac{3}{4}\)
X - 2 = 12 : \(\frac{1}{3}\)
X = 36 + 2
X = 38
e. 12 x (X - 5) + 73 = 20
12 x (X - 5) = 20 - 73
X - 5 = -53 : 12
X = \(\frac{-53}{12}\)+ 5
X = \(\frac{7}{12}\)
3(x+2)=12(6-x)+1
=> 3x +6 = 72 -12x +1
=> 3x + 6 -72 +12x -1 =0
=> 15x -67 =0
=> 15x = 67
=> x = 67/15
thanks bạn nhé.