Question

[Nguyễn Thanh Hằng]

Bài 2. Tìm số tự nhiên x, biết:

a) 120⋮𝑥;240⋮𝑥,300⋮𝑥,𝑥≥10

b) 𝑥⋮16;𝑥⋮15;𝑥⋮11,𝑥<3000

Answer 1

[ʚۜ❄ۜ♪♪♪ thiên yết cute ♪♪♪๖ミۣᶦᵈᵒᶫ✎...]

a)\(120⋮x;240⋮x;300⋮x;x\ge10\)

=> x\(\inƯC\left(120;240;300\right)\)

120=2³.3.5

240=2⁴.3.5

300=2².5².3

Ưc(120;240;300)=2².5.3=60

b)\(x⋮16;x⋮15;x⋮11;x< 3000\)

=>x\(\in BC\left\{16;15;11\right\}\)

16=2⁴

15=3.5

11=11

BC(16;15;11)=2⁴.3.5.11=2640

Answer 2

[ʚۜ❄ۜ♪♪♪ thiên yết cute ♪♪♪๖ミۣᶦᵈᵒᶫ✎...]

a)ta có \(120⋮x,240⋮x,300⋮x,x\ge10\)

=> \(x\inƯC\left(120;240;300\right)\)

120=2³.3.5

240=2⁴.3.5

300=2².5².3

ƯCLN(120,240,300)=2².3.5=60

b) ta có\(x⋮16;x⋮15;x⋮11,x< 3000\)

=>\(x\in BCNN\left(16;15;11\right)\)

16=2⁴

15=3.5

11=11

BCNN(16;15;11)=2⁴.5.3.11=2640

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