`a, 25 = 5^2`
`35 = 7 xx5`
`75 = 3 xx 5^2`
`=> (25, 35, 75) = 3 xx 5^2 xx 7 = 525`
`b, 150 = 3 xx 5^2 xx 2`.
`84 = 2^2 xx 3 xx 7`
`30 = 2 xx 3 xx 5`.
`=> x = 2 ( t//m)`.
`c, 10 = 2 xx 5`
`15 = 3 xx 5`.
`=> UC(10,15) = 0, 30, 60, 90, 120, ...`
`=> x in {0, 30, 60, 90}`.
1
25=52
35=5.7
75=3.52
→ ƯCLN (25;35;75)=5
→ ƯC (25;35;75)= Ư (5)=\(\left\{1;5\right\}\)
2
a/ta có
150 : x ; 84 : x ; 30 : x
→x ∈ ƯC (150,84,30)
\(150=2.3.5^2\\ 84=2^2.3.7\\ 30=2.3.5\)
→ ƯCLN (150,84,30)=2.3=6
→ ƯC (150,84,30)= Ư (6)=\(\left\{1;2;3;6\right\}\)
mà 0 < x < 16
nên x ∈ \(\left\{1;2;3;6\right\}\)
b/
ta có
x : 10 ; x : 15 → x ∈ BC(10,15)
10=2.5
15=3.5
→ BCNN (15,10)=2.3.5=30
→ BC(15,10)= B(30)=\(\left\{0;30;60;90;120;150;...\right\}\)
MÀ x < 100
nên x ∈ \(\left\{0;30;60;90\right\}\)