Question

1. Tìm ƯCLN và BCNN của :

a. 220,240 và 300

b. 40,75,106

c. 18, 36, 72

Answer 1

a, 220 = 2² . 5 . 11

240 = 2⁴ . 3 . 5

300 = 2² . 3 . 5²

ƯCLN(220;240;300) = 2² . 5 = 20

BCNN(220;240;300) = 2⁴ . 3 . 5² . 11 = 13200

b, 40 = 2³ . 5

75 = 3 . 5²

106 = 2 . 53

ƯCLN(40;75;106) = 1

BCNN(40;75;106) = 2³ . 3 . 5² . 53 = 31800

c, 18 = 2 . 3²

36 = 2² . 3²

72 = 2³ . 3²

ƯCLN(18;36;72) = 2 . 3² = 18

BCNN(18;36;72) = 2³ . 3² = 72

Answer 2

a)Ta có:220=2².5.11

240=2⁴.3.5

300=2².3.5²

^{\(\Rightarrow\)}\(ƯCLN\)(220;240;300)=2².5=20

\(BCNN\left(220;240;300\right)=2^4.3.5^2.11=13200\)

b)Ta có:40=2³.5

75=3.5²

106=2.53

\(\RightarrowƯCLN\)(40;75;106)=1

\(BCNN\left(40;75;106\right)=2^3.3.5^2.53=31800\)

c)Ta có:18=2.3²

36=2².3²

72=2³.3²

\(\RightarrowƯCLN\)(18;36;72)=2.3²=\(18\)

\(BCNN\left(18;36;72\right)=2^3.3^2=72\)

Answer 3

a) Ta có :

220 = \(2^2\). 5 . 11

240 = \(2^4\). 3 . 5

300 = \(2^2\). 3 . \(5^2\)

⇒ ƯCLN (220;240;300) = \(2^2\) . 3 . 5 = 60

⇒ BCNN (220;240;300) = \(2^4\) . 3 . \(5^2\) = 1200

b) Ta có :

40 = 2 . 4 . 5

75 = \(5^2\) . 3

106 = 2 . 53

⇒ ƯCLN (40;75;106) = 2 . 3 . 4 . 5 = 120

⇒ BCNN (40;75;106) = 2 . 4 . 3 . \(5^2\) . 53 = 31800

c) Ta có :

18 = 2 . \(3^2\)

36 = \(2^2\) . \(3^2\)

72 = \(2^3\) . \(3^2\)

⇒ ƯCLN (18;36;72) = 2 . \(3^2\) = 18

⇒ BCNN (18;36;72) = \(2^3\) . \(3^2\) = 72

Chúc bạn học tốt !!! =333