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a\()\) 1/2 x 2/3 : 5/6 x 5/6
=2/6 : 35/36
=1/3 x 36/35
=36/105=12/35
b\()\)11x15x56/6x35x38
=165x56/6x35x38
=9240/6x35x38
=1540x35x38
=53900x38
=2,048,200
c\()\) 2/7 x 7/5 + 2/7 - 2/7 x 6/5
=2/7x\(\left(\dfrac{7}{5}-\dfrac{2}{7}\right)\)+2/7
=2/7 x 39/35 + 2/7
=2/7 x \(\left(\dfrac{39}{35}+1\right)\)
=2/7 x 74
=148/7
` 1/2 + 3/4 - 5/6 = 6/12 + 9/12 - 10/12 = 5/12`
` ( 5/6 + 3/8) xx 2/7 = ( 15/24 + 9/24) xx 2/7 = 29/24 xx 2/7 = 29/84`
` ( 7/6 - 3/4) : 3/5 = ( 14/12 - 9/12) : 3/5 = 5/12 : 3/5 = 5/12 xx 5/3 = 25/36`
` 6/7 xx 2/3 : 5/7 = 6/7 xx 2/3 xx 7/5 = 4/5`
a: =>x=3/7+3/5=15/35+21/35=36/35
b: =>x/35=4/5-5/7=28/35-25/35=3/35
=>x=3
c: =>x<3/4+8/4=11/4
=>\(x\in\left\{0;1;2;3\right\}\)
d: =>5/3<x<5/6+24/6=29/6
=>\(x\in\left\{2;3;4\right\}\)
e: =>x<10/12-9/12=1/12
=>x=0
f: =>2/3<x<12/6-5/6=7/6
=>x=1
a: \(=\dfrac{5}{14}\left(\dfrac{2}{9}+\dfrac{7}{9}+1\right)=\dfrac{5}{14}\cdot2=\dfrac{5}{7}\)
b: \(=\dfrac{6}{8}\left(\dfrac{6}{7}-6\right)=\dfrac{6}{8}\cdot\dfrac{-36}{7}=\dfrac{-216}{56}=\dfrac{-27}{7}\)
\(\dfrac{13}{7}+\dfrac{5}{6}+\dfrac{2}{7}+\dfrac{7}{6}=\dfrac{15}{7}+\dfrac{12}{6}=\dfrac{29}{7}\)
\(\dfrac{1}{2}\times\dfrac{5}{6}+\dfrac{1}{2}\times\dfrac{11}{6}=\dfrac{1}{2}\times\left(\dfrac{5}{6}+\dfrac{11}{6}\right)=\dfrac{1}{2}\times\dfrac{16}{6}=\dfrac{4}{3}\)
Bài 2:
a: 2/6x5/3=10/18=5/9
b: 11/9x5/10=55/90=11/18
c: 3/9x6/8=1/3x3/4=1/4
d: 4/9x12/16=48/144=1/3
e: 25/15x6/7=5/3x6/7=30/21=10/7
f: 6/10x15/20=90/200=9/20
Bài 1
4/5 x 6/7= 24/35
2/9 x 1/2= 2/18= 1/9
1/2 x 8/3= 8/6= 4/3
7/9 x 6/5= 42/45= 14/15
8/7 x 5/9= 40/63
10/11 x 22/15= 220/165= 4/3
Bài 2
2/6 x 5/3= 1/3 x 5/3=5/9
11/9 x 5/10= 11/9 x 1/2= 11/18
3/9 x 6/8= 1/3 x 3/4 =3/12= 1/4
4/9 x 12/16= 4/9 x 3/4= 12/36= 1/3
25/15 x 6/7= 5/3 x 6/7= 30/21= 10/7
6/10 x 15/20= 3/5 x 3/4= 9/20
cách 1 \(\left(\dfrac{6}{11}+\dfrac{7}{5}\right)\cdot\dfrac{3}{7}\\ =\dfrac{107}{55}\cdot\dfrac{3}{7}=\dfrac{321}{385}\)cách 2 \(\left(\dfrac{6}{11}+\dfrac{7}{5}\right)\cdot\dfrac{3}{7}\\ =\dfrac{6}{11}\cdot\dfrac{3}{7}+\dfrac{7}{5}\cdot\dfrac{3}{7}\\ =\dfrac{18}{77}+\dfrac{3}{5}=\dfrac{321}{385}\)
cách 1 \(\left(\dfrac{6}{7}-\dfrac{1}{2}\right)\cdot\dfrac{2}{5}\\ =\dfrac{5}{14}\cdot\dfrac{2}{5}=\dfrac{1}{7}\) cách 2 \(\left(\dfrac{6}{7}-\dfrac{1}{2}\right)\cdot\dfrac{2}{5}\\ =\dfrac{6}{7}\cdot\dfrac{2}{5}-\dfrac{1}{2}\cdot\dfrac{2}{5}\\ =\dfrac{12}{35}-\dfrac{1}{5}=\dfrac{1}{7}\)
[ \(\dfrac{6}{11}\) + \(\dfrac{7}{5}\)] x \(\dfrac{3}{7}\)
= [ \(\dfrac{30}{55}\) + \(\dfrac{77}{55}\)] x \(\dfrac{3}{7}\)
= \(\dfrac{107}{55}\)x \(\dfrac{3}{7}\)
= \(\dfrac{321}{385}\)
[ \(\dfrac{6}{11}\) + \(\dfrac{7}{5}\)] x \(\dfrac{3}{7}\)
= \(\dfrac{6}{11}\) x \(\dfrac{3}{7}\) + \(\dfrac{7}{5}\) x \(\dfrac{3}{7}\)
= \(\dfrac{18}{77}\) + \(\dfrac{3}{5}\)
= \(\dfrac{90}{385}\) + \(\dfrac{231}{385}\)
= \(\dfrac{321}{385}\)
[ \(\dfrac{6}{7}\) - \(\dfrac{1}{2}\)] x \(\dfrac{2}{5}\)
= [ \(\dfrac{12}{14}\) - \(\dfrac{7}{14}\)] x \(\dfrac{2}{5}\)
= \(\dfrac{5}{14}\) x \(\dfrac{2}{5}\)
= \(\dfrac{1}{7}\)
[ \(\dfrac{6}{7}\) - \(\dfrac{1}{2}\)] x \(\dfrac{2}{5}\)
= \(\dfrac{6}{7}\) x \(\dfrac{2}{5}\) - \(\dfrac{1}{2}\) x \(\dfrac{2}{5}\)
= \(\dfrac{12}{35}\) - \(\dfrac{1}{5}\)
= \(\dfrac{12}{35}\) - \(\dfrac{7}{35}\)
= \(\dfrac{5}{35}\)
= \(\dfrac{1}{7}\)
a,Cách 1: (6/11 + 5/11 ) x 3/7 Cách 2 :(6/11 + 5/11) x 3/7
= 1 x 3/7 =6/11 x 3/7 + 5/11 x 3/7
= 3/7 = 18/77 + 15/77
= 3/7
b, Cách 1:3/5 x 7/9 - 3/5 x 2/9 Cách 2 :3/5 x 7/9 - 3/5 x 2/9
= 7/15 - 2/15 = 3/5 x (7/9 - 2/9 )
= 1/3 = 3/5 x 5/9
= 1/3
c, Cách 1:(6/7 - 4/7) : 2/5 Cách 2: ( 6/7- 4/7 ) : 2/5
= 2/7 : 2/5 = 6/7 : 2/5 - 4/7 : 2/5
= 5/7 = 15/7 - 10/7
= 5/7
d,Cách 1:8/15 : 2/11 + 7/15 : 2/11 Cách 2:8/15 : 2/11 +7/15 : 2/11
= 88/30 + 77/30 =(8/15+7/15) :2/11
= 11/2 = 1 : 2/11
= 11/2
Bài 2 cậu tự làm nhé !
x:6/5=19/6
x=19/6x6/5
x=19/5
7/8*6/5=42/40
x=42/40