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a) 27 × 10 = 270; 72 × 100 = 7200; 14 × 1000 = 14000
86 × 10 = 860; 103 × 10 = 10300; 452 × 1000 = 452000
358 × 10 = 3580; 1977 × 100 = 197700; 300 × 1000 = 300000
b) 80 :10 = 8; 400 : 100 = 4 ;6000 : 1000 = 6
300 : 10 = 30; 4000 : 100 = 40 ; 60000 : 1000 = 60
2000 :10 = 200; 40000 :100 = 400 ;600000 : 1000 = 600
c) 64 × 10 = 640; 32 × 100 = 3200; 95 × 1000 = 95000
640 : 10 = 64; 3200 : 100 = 32; 95000 : 1000 = 95
1. a) 76 x 34 + 86 x 34
= 34 x ( 76 + 86 )
= 34 x 162
= 5508
b) 1 x 3 + 1 x 4 + 1 x 7 + 1
= 1 x 3 + 1 x 4 + 1 x 7 + 1 x 1
= 1 x ( 3 + 4 + 7 + 1 )
= 1 x 15
= 15
a) 72/45 x 35/36= 8/5 x 35/36 =280/180=14/9.
b)1/2:3/4+1/6:3/4 =(1/2+1/6) : 3/4 =8/12:3/4 = 24/36=2/3
c) 2/3x4/5+1/3=2/3+1/3x4/5+1/3=4/3x4/15=16/45.
Nếu sai thông cảm cho mình nhé. Bạn ko k cũng ko sao đâu.
a.(64 - 32 ) :8 = 32 : 8 = 4
b. 36 x 2 x7 + 36 x 86
= 36 x (14 + 86)
= 36 x 100
= 3600
68:8 - 32 : 8
= ( 68 - 32): 8
= 36 : 8
= 4,5
72 x 7 + 36 x 86
= 72 x 7 + 36 x 2 x 43
= 72 x 7 + 72 x 43
= 72 x ( 7 + 43)
= 72 x 50
= 3600
a: =428(36+64)=42800
b: =512(47-37)=5120
c: =72x100=7200
a) Ta có \(\dfrac{72}{95}\times\dfrac{105}{105}=\dfrac{72}{95}\times1=\dfrac{72}{95}=\dfrac{72}{95}\)
Vậy \(\dfrac{72}{95}=\dfrac{72}{95}\times\dfrac{105}{105}\)
b) Ta có \(\dfrac{72}{95}\times\dfrac{99}{98}=\dfrac{72}{95}\times\left(1+\dfrac{1}{98}\right)=\dfrac{72}{95}\times1+\dfrac{72}{95}\times\dfrac{1}{98}=\dfrac{72}{95}+\dfrac{72}{95}\times\dfrac{1}{98}>\dfrac{72}{95}\)Vậy \(\dfrac{72}{95}< \dfrac{72}{95}\times\dfrac{99}{98}\)
a) 72/95 ... 72/95 x 105/105
72/95 ... 72/95 x 1 ( 105/105 = 1 )
72/95 = 72/95 x 105/105
b) 72/95 ... 72/95 x 99/98
72/95 x 1 ... 72/95 x 99/98 ( 99/98 > 1 )
72/95 < 72/95 x 99/98
1: \(=\dfrac{1}{3}\cdot\dfrac{3}{7}\cdot\dfrac{1}{2}=\dfrac{1}{7\cdot2}=\dfrac{1}{14}\)
2: =5/12+1/7
=35/84+12/84=47/84
3: =8(8/9-6/9)
=8*2/9=16/9
4: \(=\dfrac{5}{12}\cdot\dfrac{12}{5}=1\)
5: =16/5+6
=16/5+30/5=46/5
6: =10*1/2-10*1/5
=5-2=3
\(\dfrac{73}{72}=1+\dfrac{1}{72}\)
\(\dfrac{43}{42}=1+\dfrac{1}{42}\)
\(\dfrac{53}{52}=1+\dfrac{1}{52}\)
\(\dfrac{65}{64}=1+\dfrac{1}{64}\)
\(\dfrac{87}{86}=1+\dfrac{1}{86}\)
mà \(\dfrac{1}{42}>\dfrac{1}{52}>\dfrac{1}{64}>\dfrac{1}{72}>\dfrac{1}{86}\left(42< 52< 64< 72< 86\right)\)
nên \(\dfrac{43}{42}>\dfrac{53}{52}>\dfrac{65}{64}>\dfrac{73}{72}>\dfrac{87}{86}\)
a) `1/2 xx 5/4 + 1/2 xx 3/4 + 1/2`
`=1/2 xx (5/4 + 3/4 + 1)`
`=1/2 xx 3`
`=3/2`
b) `72/95 xx 64/72 xx 95/72 xx 14/86 xx 72/64 xx 86/14`
`=(72xx64xx95xx14xx72xx86)/(95xx72xx72xx86xx64xx14)`
`= 1`.
a)1/2.(5/4+3/4+1)
=1/2.3
=3/2