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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
a) = 1/2 - 1/2 + 1/3 -1/3 + 1/4 - 1/4 + 1/5 - 1/5 + 1/6
= 0 + 0 + 0 + 0 + 1/6
= 1/6
b) 2/3 + 2/4 - 2/4 + 2/5 - 2/5 + 2/6 - 2/6 + 2/7 - 2/7 + 28
= 2/3 + 28
= 86/3
[tick cho mik nha]
Tính:
2/7 + 5/7=1
8/15 + 6/15 =14/15
2/9 + 3/9 + 4/9=9/9=1
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 = 1/5 + 3/5
7/9 + 1/9 < 7/9 + 1/9 + 1/9
3/7 + 2/7 < 3/7 + 4/7
1/5 + 3/5 < 2/5 + 3/5
Tính:
2/7 + 5/7=1
8/15 + 6/15 =14/15
2/9 + 3/9 + 4/9=9/9=1
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 = 1/5 + 3/5
7/9 + 1/9 < 7/9 + 1/9 + 1/9
3/7 + 2/7 < 3/7 + 4/7
1/5 + 3/5 < 2/5 + 3/5
`( 2/3 xx 4/5) xx 5/6`
`= 8/15 xx 5/6`
`= 40/90`
`=4/9`
__
`( 2/3 xx 4/5) xx 5/6`
`= 2/3 xx (4/5 xx 5/6)`
`= 2/3 xx 2/3`
`= 4/9`
-------
`(1/2 + 1/3) xx 1/5`
`= ( 3/6 +2/6) xx 1/5`
`= 5/6 xx1/5`
`= 5/30`
`=1/6`
__
`(1/2 + 1/3) xx 1/5`
`=1/2 xx 1/5 + 1/3 xx 1/5`
`= 1/10 + 1/15`
`=1/6`
a)
c1
`(2/3xx4/5)xx5/6`
`=8/15xx5/6`
`=4/9`
c2
`(2/3xx4/5)xx5/6`
`=2/3xx4/5xx5/6`
`=2/3xx5/6xx4/5`
`=5/9xx4/5`
`=4/9`
b)
c1
`(1/2+1/3)xx1/5`
`=(3/6+2/6)xx1/5`
`=5/6xx1/5`
`=1/6`
c2
`(1/2+1/3)xx1/5`
`=1/2xx1/5+1/3xx1/5`
`=1/10+1/15`
`=3/30+2/30`
`=5/30=1/6`
a: \(=\dfrac{2}{3}\cdot\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{2}{3}\cdot\dfrac{2}{3}=\dfrac{4}{9}\)
b: \(=\dfrac{5}{6}\cdot\dfrac{1}{5}=\dfrac{1}{6}\)
a. C1: \(\dfrac{8}{15}.\dfrac{5}{6}=\dfrac{4}{9}\)
C2: \(\dfrac{2}{3}.\dfrac{4}{5}.\dfrac{5}{6}=\dfrac{2.4.5}{3.5.3.2}\)
Triệt tiêu phần giống nhau ở tử và mẫu ta có
\(=\dfrac{4}{9}\)
b. \(C1:\left(\dfrac{1}{2}+\dfrac{1}{3}\right).\dfrac{1}{5}=\dfrac{5}{6}.\dfrac{1}{5}=\dfrac{1}{6}\)
C2: \(\dfrac{1}{2}.\dfrac{1}{5}+\dfrac{1}{3}.\dfrac{1}{5}=\dfrac{1}{10}+\dfrac{1}{15}=\dfrac{1}{6}\)
2/5 + 1/2
= 4/10 + 5/10
= 9/10
\(\dfrac{2}{5}+\dfrac{1}{2}=\dfrac{4}{10}+\dfrac{5}{10}=\dfrac{9}{10}\)