B1
Ta có:58=2.29
42=2.3.7
ƯCLN(28,42)=2
ƯC(28,42)=Ư(2)={1;2}
B2
B,Ta có:30=2.3.5
45=32.5
BCNN(30,45)=2.32.5=90
BC(30,45)=B(60)={0;60;120;180;...}
MẤY CÁI CÒN LẠI TƯƠNG Tự NHÉ
1, \(58=2.29\)
\(42=2.3.7\)
\(\RightarrowƯC\left(58,42\right)=2\)
2,
TH1 : \(30=2.3.5\)
\(45=3^2.5\)
\(\Rightarrow BC\left(30,45\right)=2.3^2.5=90\)
TH2 : \(56=2^3.7\)
\(70=2.5.7\)
\(126=2.3^2.7\)
\(\Rightarrow BC\left(56,70,126\right)=2^3.3^2.5.7=2520\)
TH3 : \(39=3.13\)
\(65=5.13\)
\(91=7.13\)
\(\Rightarrow BC\left(39,65,91\right)=3.5.7.13=1365\)
Câu 1
Ta có
58=2x29
42=2x3x7
=>ƯCLN(58;42)=21=2
ƯC(58;42)=Ư(2)={1;2}
Câu 2
b, Ta có
30=2x3x5
45=32x5
=>BCNN(30;45)=2x32x5=90
BC(30;45)=B(90)={0;90;180;270;......}
c, (56;70;126)
56=23x7
70=2x5x7
126=2x32x7
=>BCNN(56;70;126)=23x32x5x7=2520
BC(56;70;126)=B(2520)={0;2520;5040;....}
d, (39;65;91)
39=3x13
65=5x13
91=7x13
=>BCNN(39;65;91)=3x5x7x13=1365
Bc(39;65;91)=B(1365)={0;1365;2730;....}
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