ta co 

9 = 3^2

15 = 3 x 5

bcnn ( 9 ;15) = 3^2 x 5 =45

ta có  : 9=3²

           15=3x5

BCNN(9,15)=3²x5=45

 /Đáp án A nha/.............Học tốt ............/cho mk 1 tíck///
    

A . BCNN(a,b,1) = BCNN(a,b) nhé

HT

Đáp án "A" Đúng .

\(36=2^2\cdot3^2\)

\(48=3\cdot2^4\)

=>\(ƯCLN\left(36;48\right)=2^2\cdot3=12\)

\(BCNN\left(36;48\right)=2^4\cdot3^2=16\cdot9=144\)

\(36=2^2.3^2\)

\(48=2^4.3\)

\(ƯCLN=2^2.3=12\)

\(BCNN=2^4.3^2=144\)

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^^

\(16=2^4\)

\(25=5^2\)

\(30=2\cdot3\cdot5\)

=>\(BCNN\left(16;25;30\right)=2^4\cdot5^2\cdot3=16\cdot25\cdot3=16\cdot75=1200\)

\(3,\\ 65=5.13\\ 80=5.2^4\\ BCNN\left(65;80\right)=5.13.2^4=1040\\ 4,\\ 16=2^4\\ 25=5^2\\ 30=2.3.5\\ BCNN\left(16;25;30\right)=2^4.3.5^2=1200\)

a: \(56=2^3\cdot7;70=2\cdot5\cdot7;126=3^2\cdot2\cdot7\)

=>\(BCNN\left(56;70;126\right)=3^2\cdot2^3\cdot5\cdot7=2520\)

b: \(9=3^2;10=2\cdot5;11=11\)

=>\(BCNN\left(10;9;11\right)=3^2\cdot10\cdot11=990\)

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