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\(x+2\dfrac{1}{4}=4\dfrac{5}{6}\)
\(x=4\dfrac{5}{6}-2\dfrac{1}{4}\)
\(x=4+\dfrac{5}{6}-2-\dfrac{1}{4}\)
\(x=2+\dfrac{7}{12}\)
\(x=\dfrac{31}{12}\)
_____________
\(9\dfrac{3}{5}-x=3\dfrac{3}{8}\)
\(x=9\dfrac{3}{5}-3\dfrac{3}{8}\)
\(x=9+\dfrac{3}{5}-3-\dfrac{3}{8}\)
\(x=6+\dfrac{9}{40}\)
\(x=\dfrac{249}{40}\)
\(x+2\dfrac{1}{4}=4\dfrac{5}{6}\)
\(=>x+\dfrac{9}{4}=\dfrac{29}{6}\)
\(=>x=\dfrac{29}{6}-\dfrac{9}{4}=\dfrac{58}{12}-\dfrac{27}{12}\)
\(=>x=\dfrac{31}{12}\)
_______
\(9\dfrac{3}{5}-x=3\dfrac{3}{8}\)
\(=>\dfrac{48}{5}-x=\dfrac{27}{8}\)
\(=>x=\dfrac{48}{5}-\dfrac{27}{8}=\dfrac{384}{40}-\dfrac{135}{40}\)
\(=>x=\dfrac{249}{40}\)
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= \(\dfrac{12}{15}:\dfrac{7}{3}=\dfrac{12}{35}\)
\(c)x:\dfrac{5}{4}=\dfrac{9}{5}+\dfrac{1}{2}\)
\(x:\dfrac{5}{4}=\dfrac{23}{10}\)
\(x=\dfrac{23}{10}\times\dfrac{5}{4}\)
\(x=\dfrac{23}{8}\)
a) \(x:3\frac{5}{6}=2\frac{8}{15}\) b) \(\frac{12}{5}:x+\frac{4}{3}=3\frac{2}{3}\)
\(x:\frac{23}{6}=\frac{38}{15}\) \(\frac{12}{5}:x+\frac{4}{3}=\frac{11}{3}\)
\(x=\frac{38}{15}\times\frac{23}{6}\) \(\frac{12}{5}:x=\frac{11}{3}-\frac{4}{3}\)
\(x=\frac{437}{45}\) \(\frac{12}{5}:x=\frac{7}{3}\)
\(x=\frac{12}{5}:\frac{7}{3}\)
\(x=\frac{36}{35}\)
a: \(x+6\dfrac{1}{8}=8\)
=>\(x+\dfrac{49}{8}=\dfrac{64}{8}\)
=>\(x=\dfrac{64}{8}-\dfrac{49}{8}=\dfrac{15}{8}\)
b: \(\dfrac{11}{2}\cdot x=\dfrac{1}{5}:\dfrac{1}{3}\)
=>\(x\cdot\dfrac{11}{2}=\dfrac{1}{5}\cdot3=\dfrac{3}{5}\)
=>\(x=\dfrac{3}{5}:\dfrac{11}{2}=\dfrac{3}{5}\cdot\dfrac{2}{11}=\dfrac{6}{55}\)
c: \(x\cdot\dfrac{3}{5}+\dfrac{2}{5}\cdot x=\dfrac{4}{9}+\dfrac{1}{3}\)
=>\(x\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{4}{9}+\dfrac{3}{9}\)
=>\(x\cdot1=\dfrac{7}{9}\)
=>\(x=\dfrac{7}{9}\)
Bài 1: tính: a) 8 và 5/9 : 5 và 1/2 b) 7 và 3/4 - 2 và 1/8 c) 1 và 3/4 x 2 và 5/6 d) 7 - 2 và 2/3 e) 2 và 3/7 x 1 và 3/4 g) 5 và 1/3 : 3 và 1/5 Bài 2: tìm X: X : 3 và 1/3= 2 và 2/5 + 7/10 Và là biểu thị cho hỗn số nhé
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) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3
c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21
A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3
c) TƯƠNG TỰ CÂU A VÀ B
* HOKTOT*
NHA
B=1 x 2 + 2 x 3 + 3 x 4 + 4 x 5 +5 x 6 + ........... + 2015 x 2016
3xB=1 x 2x3 + 2 x 3x3 + 3 x 4x3 + 4 x 5x3 +5 x 6x3 + ........... + 2015 x 2016x3
=1x2x3+2x3x(4-1)+3x4x(5-2)+4x5x(6-3)+...+2014x2015(2016-2013)+2015x2016(2017-2014)
=1x2x3+2x3x4-1x2x3+3x4x5-2x3x4+4x5x6-3x4x5+..+2014x2015x2016-2013x2014x2015+2015x2016x2017-2014x2015x2016
các số hạng tự triệt tiêu nhau
còn lại (2015x2016x2017)
B= (2015x2016x2017)/3=2015x672x2017
2015=5.43
672=.3.4.7.8
=> B chia hết cho 2,4,6,7,8
không chia hết cho 9
b: Ta có: \(\dfrac{12}{5}:x+\dfrac{4}{3}=3+\dfrac{2}{3}\)
\(\Leftrightarrow\dfrac{12}{5}:x=3-\dfrac{2}{3}=\dfrac{7}{3}\)
hay \(x=\dfrac{12}{5}:\dfrac{7}{3}=\dfrac{36}{35}\)