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a) \(x.\frac{3}{4}=\frac{4}{5}.2\)
\(x.\frac{3}{4}=\frac{8}{5}\)
\(x=\frac{8}{5}:\frac{3}{4}=\frac{32}{15}\)
b) \(x:1\frac{1}{7}=2\frac{2}{3}\)
\(x:\frac{8}{7}=\frac{8}{3}\)
\(x=\frac{8}{3}.\frac{8}{7}=\frac{64}{21}\)
c) \(x-1\frac{2}{5}=4\frac{1}{6}-2\frac{2}{3}\)
\(x-\frac{7}{5}=\frac{25}{6}-\frac{8}{3}=\frac{3}{2}\)
\(x=\frac{3}{2}+\frac{7}{5}=\frac{29}{10}\)
d) \(2\frac{2}{3}+x:\frac{3}{2}=2\frac{1}{3}\)
\(\frac{8}{3}+x:\frac{3}{2}=\frac{7}{3}\)vô lí vì 8/3 lớn hơn 7/3
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= \(\dfrac{12}{15}:\dfrac{7}{3}=\dfrac{12}{35}\)
\(c)x:\dfrac{5}{4}=\dfrac{9}{5}+\dfrac{1}{2}\)
\(x:\dfrac{5}{4}=\dfrac{23}{10}\)
\(x=\dfrac{23}{10}\times\dfrac{5}{4}\)
\(x=\dfrac{23}{8}\)
Bài 1
a) 3 2/5 - 1/2
= 17/5 - 1/2
= 34/10 - 5/10
= 29/10
b) 4/5 + 1/5 × 3/4
= 4/5 + 3/20
= 16/20 + 3/20
= 19/20
c) 3 1/2 × 1 1/7
= 7/2 × 8/7
= 4
d) 4 1/6 : 2 1/3
= 25/6 : 7/3
= 25/14
Bài 2
a) 3 × 1/2 + 1/4 × 1/3
= 3/2 + 1/12
= 18/12 + 1/12
= 19/12
b) 1 4/5 - 2/3 : 2 1/3
= 9/5 - 2/3 : 7/3
= 9/5 - 2/7
= 63/35 - 10/35
= 53/35
\(\left(\frac{5}{7}+\frac{2}{3}\right).\frac{7}{11}\)
C1:\(=\frac{29}{21}.\frac{7}{11}=\frac{29}{33}\)(tính trong ngoặc rồi mới nhân)
C2:\(=\frac{5}{7}.\frac{7}{11}+\frac{2}{3}.\frac{7}{11}=\frac{5}{11}+\frac{14}{33}=\frac{29}{33}\)(dùng tính chất phân phối)
Những câu khác bn tự làm nha
\(x:\frac{8}{9}=1\frac{3}{7}\)
\(x:\frac{8}{9}=\frac{10}{7}\)
\(x=\frac{10}{7}.\frac{8}{9}\)
\(x=\frac{80}{63}\)
\(x-1\frac{1}{4}=2\frac{1}{8}\)
\(x-\frac{5}{4}=\frac{17}{8}\)
\(x=\frac{17}{8}+\frac{5}{4}\)
\(x=\frac{17}{8}+\frac{10}{8}\)
\(x=\frac{27}{8}\)
\(x:\frac{8}{9}=1\frac{3}{7}\)
\(x:\frac{8}{9}=\frac{10}{7}\)
\(x=\frac{10}{7}\times\frac{8}{9}\)
\(x=\frac{80}{63}\)
#Y/n
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 = \(\frac{7}{12}\)
a) X x 3 và 1/3 = 3 và 1/3 :4 và 1/4
=> X x 10/3 = 10/3 : 17/4
=> X = 10/3 : 17/4 : 10/3
=> X = ( 10/3 : 10/3 ) ; 17/4
=> X = 1 : 17/4 = 4/17
Vậy X = 4/17
b) 5 và 2/3 : X = 3 và 2/3 - 2 và 1/2
=> 17/3 : X = 11/3 - 5/2
=> 17/3 : X = 7/6
=> X = 17/3 : 7/6 = 34/7
Vậy x = 34/7
c) X x 3,9 + X x 0.1 = 2,7
=> X x ( 3,9 + 0,1 ) = 2,7
=> X x 4 = 2,7
=> X = 2,7 : 4
=> X = 0,675
Vậy x = 0,675