Nội dung bài giảng
Bài 134. Điền kí hiệu \(∈\) hoặc \(\notin\) vào ô vuông cho đúng:
a) \(4\) \(\square\) \(ƯC (12, 18)\); b) \(6\) \(\square\) \(ƯC (12, 18)\);
c) \(2\) \(\square\) \(ƯC (4, 6, 8)\); d) \(4\) \(\square\) \(ƯC (4, 6, 8)\);
e) \(80\) \(\square\) \(BC (20, 30)\); g) \(60\) \(\square\) \(BC (20, 30)\)
h) \(12\) \(\square\) \(BC (4, 6, 8)\); i) \(24\) \(\square\) \(BC (4, 6, 8)\)
Bài giải:
\(12=2^2.3\)
\(18=2.3^2\)
\(ƯCLN(12,18)= 2.3=6\)
\(4=2^2\)
\(6=2.3\)
\(8=2^3\)
\(ƯCLN(4,6,8)= 2\)
\(BCNN(4,6,8)=2^3.3=24\)
\(20=2^2.5\)
\(30=2.3.5\)
\(BCNN(20,30)=2^2.3.5=60\)
a) \(4\) \(\notin\) \(ƯC (12, 18)\); b) \(6 ∈ ƯC (12, 18)\);
c) \(2 ∈ ƯC (4, 6, 8)\); d) \(4 \notin ƯC (4, 6, 8)\);
e) \(80 \notin BC (20, 30)\); g) \(60 ∈ BC (20, 30)\)
h) \(12 \notin BC (4, 6, 8)\); i) \( 24 ∈ BC (4, 6, 8)\)