ƯCLN ( 180 , 320 , 780) = 20

ƯCLN ( 1020 , 380 , 960) = 20

trình bày ra 

ƯCLN ( 180 ; 320 ; 780 )

180 = 2² . 3² . 5

320 = 2⁶ . 5

780 = 2² . 3 . 5 . 13

=> ƯCLN ( 180 ; 320 ; 780 ) = 2². 5 = 20

ƯCLN ( 1020 ; 380 ; 960 )

1020 = 2² . 3 . 5 . 17

380 = 2² . 5 . 19

960 = 2⁶ . 3 . 5

=> ƯCLN ( 1020 ; 380 ; 960 ) = 2² . 5 = 20

Ta có :

\(180=2^2.3^2.5\)

\(320=2^6.5\)

\(780=2^2.3.5.13\)

=> \(UCLN\left(180,320,780\right)=2^2.3.5=60\)

Ta có :

\(1020=2^2.3.5.17\)

\(380=2^2.5.19\)

\(960=2^6.3.5\)

=> \(UCLN\left(1020,380,960\right)=2^2.5=20\)

Câu 1: B

Câu 2: C

a: UCLN=30

BCNN=360

b: UCLN=12

BCNN=720

\(480=2^5.3.5\)

\(288=2^5.3^2\)

\(160=2^5.5\)

\(\text{Ư}CLN=2^5.3=96\)

\(B\left(96\right)=\left\{0;96;192;288;384;...\right\}\)

ƯCLN (480;288;160)

Phân tích ra thừa số nguyên tố, ta có kết quả sau :

480 = 2^5 . 3 . 5

288 = 2^5 . 3^2

160 = 2^5 . 5

Chọn 2

Suy ra UwCLN (480;288;160)=2^5=32

B(32) = {0;32;64;96;128;160;192;...}
 

1)

a) 18 = 2.3²

30 = 2.3.5

ƯCLN(18; 30) = 2.3 = 6

b) 24 = 2³.3

48 = 2⁴.3

ƯCLN(24; 48) = 2³.3 = 24

c) 18 = 2.3²

30 = 2.3.5

15 = 3.5

ƯCLN(18; 30; 15) = 3

d) 24 = 2³.3

48 = 2⁴.3

36 = 2².3²

ƯCLN(24; 48; 36) = 2².3 = 12

2) a) 174 = 18 . 9 + 12

18 = 12 . 1 + 6

12 = 6 . 2

Vậy ƯCLN(174; 18) = 6

b) 124 = 16 . 7 + 12

16 = 12 . 1 + 4

12 = 4 . 3

⇒ ƯCLN(124; 16) = 4

⇒ BCNN(124; 16) = 124 . 16 : 4 = 496