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a) Có 40 = 23 . 5
52 = 22 . 13
=> BCNN(40,52) = 23 . 5 . 13 = 520
b) Có 42 = 2.3.7
70 = 2.5.7
180 = 22.32.5
=> BCNN (42,70,180) = 22.32.5.7 = 1260
c) Có 9 = 32
10 = 2.5
11 = 11
=> BCNN (9,10,11) = 32.2.5.11 = 990
![](https://rs.olm.vn/images/avt/0.png?1311)
42 = 2.3.7
70 = 2.5.7
180 = 22.32.5
BCNN(42,70,180) = 22.32.5.7 = 1260
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:8=23
10=2.5
24=24.5
BCNN(...)=23.5=24.5=40
b)Ta có:
16=24
24=23.3
BCNN(...)=24.3=48
c)Ta có:
60=22.3.5
140=22.5.7
BCNN(...)=22.3.5.7=420
Mấy bài sau bn cứ lm như thế này nhé^^
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(24=2^3\cdot3;40=2^3\cdot5\)
=>\(ƯCLN\left(24;40\right)=2^3=8\)
=>\(ƯC\left(24;40\right)=\left\{1;-1;2;-2;4;-4;8;-8\right\}\)
b: \(12=2^2\cdot3;52=2^2\cdot13\)
=>\(ƯCLN\left(12;52\right)=2^2=4\)
=>\(ƯC\left(12;52\right)=\left\{1;-1;2;-2;4;-4\right\}\)
c: \(45=3^2\cdot5;180=2^2\cdot3^2\cdot5\)
=>\(ƯCLN\left(45;180\right)=3^2\cdot5=45\)
=>\(ƯC\left(45;180\right)=\left\{1;-1;3;-3;5;-5;9;-9;15;-15;45;-45\right\}\)
d: \(27=3^3;45=3^2\cdot5;75=3\cdot5^2\)
=>\(ƯCLN\left(27;45;75\right)=3\)
=>\(ƯC\left(27;45;75\right)=\left\{1;-1;3;-3\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)Ta có 60 = 2 2 .3. 5; 280 = 2 3 .5.7
BCNN(60; 280) = 2 3 . 3.5.7= 840
b) Ta có: 84 = 2 2 .3.7; 108 = 2 2 . 3 3
BCNN(84; 108) = 2 2 . 3 3 .7 = 756
c) Ta có: 13 =13; 15= 3.5
BCNN(13; 15) = 13.3.5= 195.
d) Ta có; 10 = 2.5; 12 = 2 2 .3; 15 = 3.5
BCNN(10;12; 15) = 2 2 .3.5 = 60
e) Ta có: 8 = 2 3 ; 9 = 3 2 ; 11 = 11
BCNN(8; 9; 11) = 2 3 . 3 2 .11= 792
f) Ta có: 24 = 3. 2 3 ; 40 = 2 3 .5; 168 = 2 3 .3.7
BCNN(24; 40; 168)= 2 3 .3. 5.7= 840
![](https://rs.olm.vn/images/avt/0.png?1311)
3:
a: \(40=2^3\cdot5;24=2^3\cdot3\)
=>\(ƯCLN\left(40;24\right)=2^3=8\)
=>\(ƯC\left(40;24\right)=Ư\left(8\right)=\left\{1;-1;2;-2;4;-4;8;-8\right\}\)
b: \(12=2^2\cdot3;52=2^2\cdot13\)
=>\(ƯCLN\left(12;52\right)=2^2=4\)
=>\(ƯC\left(12;52\right)=\left\{1;-1;2;-2;4;-4\right\}\)
c: \(36=2^2\cdot3^2;990=2\cdot3^2\cdot5\cdot11\)
=>\(ƯCLN\left(36;990\right)=3^2\cdot2=18\)
=>\(ƯC\left(36;990\right)=\left\{1;-1;2;-2;3;-3;6;-6;9;-9;18;-18\right\}\)
2:
a: \(12=2^2\cdot3;18=3^2\cdot2\)
=>\(ƯCLN\left(12;18\right)=2\cdot3=6\)
b: \(12=2^2\cdot3;10=2\cdot5\)
=>\(ƯCLN\left(12;10\right)=2\)
c: \(24=2^3\cdot3;48=2^4\cdot3\)
=>\(ƯCLN\left(24;48\right)=2^3\cdot3=24\)
d: \(300=2^2\cdot3\cdot5^2;280=2^3\cdot5\cdot7\)
=>\(ƯCLN\left(300;280\right)=2^2\cdot5=20\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 8 = 2³
10 = 2.5
20 = 2².5
BCNN(8; 10; 20) = 2³.5 = 40
b) 16 = 2⁴
24 = 2³.3
BCNN(16; 24) = 2⁴.3 = 48
c) 60 = 2².3.5
140 = 2².5.7
BCNN(60; 140) = 2².3.5.7 = 420
d) 8 = 2³
9 = 3²
11 = 11
BCNN(8; 9; 11) = 2³.3².11 = 792
e) 24 = 2³.3
40 = 2³.5
162 = 2.3⁴
BCNN(24; 40; 162) = 2³.3⁴.5 = 3240
f) 56 = 2³.7
70 = 2.5.7
126 = 2.3².7
BCNN(56; 70; 126) = 2³.3².5.7 = 2520
g) 28 = 2².7
20 = 2².5
30 = 2.3.5
BCNN(28; 20; 30) = 2².3.5.7 = 420
h) 34 = 2.17
32 = 2⁵
20 = 2².5
BCNN(34; 32; 20) = 2⁵.5.17 = 2720
k) 42 = 2.3.7
70 = 2.5.7
20 = 2².5
BCNN(42; 70; 20) = 2².3.5.7 = 420
l) 9 = 3²
10 = 2.5
11 = 11
BCNN(9; 10; 11) = 2.3².5.11 = 990
a. 40 = 23.5
52 = 22.13
BCNN(40,52) = 23.5.13 = 520
b. 42 = 2.3.7
70 = 2.5.7
180 = 22.32.5
BCNN(42,70,180) = 22.32.5.7 = 1260
c. Vì 9,10 và 11 là các số đôi một nguyên tố cùng nhau nên:
BCNN(9,10,11) = 9.10.11 = 990
a ) 40 và 52
40 = 23 x 5
52 = 22 x 13
=> BCNN(40,52) = 23 x 5 x 13 = 520
b|) 42 , 70 và 180
42 = 2 x 3 x 7
70 = 2 x 5 x 7
180 = 22 x 32 x 5
=> BCNN( 42,70,180 ) = 22 x 32 x 5 x 7 = 1260
c) 9,10 và 11
9 = 32
10 = 2 x 5
11 = 11
=>BCNN ( 9,10,11 ) = 2 x 32 x 5 x 11 = 990