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Bài giải
\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\)
\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{394}{90}\)
\(\frac{15}{17}-\frac{11}{13}+\frac{3}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)
\(\frac{9}{12}\text{ x }\frac{4}{3}\text{ : }\frac{8}{5}=\frac{9}{12}\text{ x }\frac{4}{3}\text{ x }\frac{5}{8}=\frac{9\text{ x }4\text{ x }5}{12\text{ x }3\text{ x }8}=\frac{5}{8}\)
\(\frac{4}{5}\text{ x }\frac{15}{8}\text{ : }\frac{5}{7}=\frac{4}{5}\text{ x }\frac{15}{8}\text{ x }\frac{7}{5}=\frac{4\text{ x }15\text{ x }7}{5\text{ x }8\text{ x }5}=\frac{21}{10}\)
\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\)
\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{197}{45}\)
\(\frac{15}{17}-\frac{11}{13}+\frac{1}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)
\(\frac{9}{12}\times\frac{4}{3}:\frac{8}{5}=1:\frac{8}{5}=\frac{5}{8}\)
\(\frac{4}{5}\times\frac{15}{8}:\frac{5}{7}=\frac{3}{2}:\frac{5}{7}=\frac{21}{10}\)
a: \(x+\dfrac{3}{9}=\dfrac{7}{6}\cdot\dfrac{2}{3}\)
=>\(x+\dfrac{1}{3}=\dfrac{14}{18}=\dfrac{7}{9}\)
=>\(x=\dfrac{7}{9}-\dfrac{1}{3}=\dfrac{7}{9}-\dfrac{3}{9}=\dfrac{4}{9}\)
b: \(x-\dfrac{2}{3}=\dfrac{1}{8}:\dfrac{5}{4}\)
=>\(x-\dfrac{2}{3}=\dfrac{1}{8}\cdot\dfrac{4}{5}=\dfrac{1}{10}\)
=>\(x=\dfrac{1}{10}+\dfrac{2}{3}=\dfrac{3+20}{30}=\dfrac{23}{30}\)
Tìm x biết :
45 - [ ( 72 - 8 . x ) : 4 + 7 ] . 3 = 0
[ ( 72 - 8 . x ) :4 + 7 ] . 3 = 45 - 0
[ ( 72 - 8 . x) : 4 + 7 ] . 3 = 45
( 72 - 8 . x ) : 4 + 7 = 45 : 3
( 72 - 8 . x ) : 4 + 7 = 15
( 72 - 8 . x ) : 4 = 15 - 7
( 72 - 8 . x ) : 4 = 8
72 - 8 . x = 8 × 4
72 - 8 . x = 32
8 . x = 72 - 32
8 . x = 40
x = 40 : 8
x = 5
Vậy x = 5
\([\left(72-8\cdot x\right):4+7]\cdot3=45-0\)
\([\left(72-8\cdot x\right):4+7]\cdot3=45\)
\(\left(72-8\cdot x\right):4+7=45:3\)
\(\left(72-8\cdot x\right):4+7=15\)
\(\left(72-8\cdot x\right):4=15-7\)
\(\left(72-8\cdot x\right):4=8\)
\(72-8\cdot x=8\cdot4\)
\(72-8\cdot x=32\)
\(8x=72-32\)
\(8x=40\)
\(x=40:8\)
\(x=5\)
Ta thấy các số chia cho 2 dư 3 phải có tận cùng là 3.Vậy số đó là 13.
`a, 2/3 +3/4 = (8+9)/12=17/12.`
`1 1/3+4/5 = 4/3 + 4/5 = (20+12)/15=32/15`.
`=> x=2.`
`b, 5/6-1/4=(20-6)/24=7/12`.
`2 1/3-2/5= 7/3-2/5 = (35-6)/15=29/15`.
`=> x=1`.
Kết quả nè bạn ơi;
A; 3/4 + 2/5=23/20
B;7/4 - 1/2=5/4
C;4/9 x 6/8=24/72
D;14/5 : 7/8=112/35
a, 23/4 : 3 + 9/4 x 1/3 - 3/8
= 7,8 + 12,22 - 3,8
= 20,02 - 3,8
=16,22
b, 3/5 : 5/6 : 6/7 : 7/8 + 2/5 +23/35
=3/5 x 6/5 x 7/6 x 8/7 + 2/5 + 23/35
=24/25 + 2/5 + 23/35
=1/5 x(24/5 + 2 +23/7)
=1/5 x 353/35
=353/175
a; \(\dfrac{2}{5}\) x \(\dfrac{3}{4}\) + \(\dfrac{6}{15}\) : \(\dfrac{4}{9}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{2}{5}\) x \(\dfrac{9}{4}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{9}{10}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{45}{10}\)
= \(\dfrac{48}{10}\)
= \(\dfrac{24}{5}\)
b; \(\dfrac{25}{12}\) x \(\dfrac{18}{35}\) x \(\dfrac{63}{24}\)
= \(\dfrac{15}{14}\) x \(\dfrac{63}{24}\)
= \(\dfrac{45}{16}\)
c; 4\(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) : 5\(\dfrac{1}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{2}\) : \(\dfrac{11}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{11}\)
= \(\dfrac{99}{22}\) + \(\dfrac{2}{22}\)
= \(\dfrac{101}{22}\)
`4/5 +1/4 xx 2/5`
`=4/5 + 1/10`
`=8/10+1/10`
`=9/10`
________________________
`7/12 +3/4:3/8 - 1/4`
`=7/12 +3/4 xx 8/3 -1/4`
`=7/12 + 2-1/4`
`=7/12 +24/12 - 3/12`
`=28/12`
`=7/3`
\(\dfrac{4}{5}+\dfrac{1}{4}\) x \(\dfrac{2}{5}\) \(=\dfrac{4}{5}+\dfrac{1}{10}=\dfrac{9}{10}\)
\(\dfrac{7}{12}+\dfrac{3}{4}:\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{7}{12}+2-\dfrac{1}{4}=\dfrac{7}{4}\)