\(x\inƯC\left(70;84;120\right)\)
\(70=2.5.7\)
\(84=2^2.3.7\)
\(120=2^3.3.5\)
\(ƯCLN\left(70;84;120\right)=2\)
Từ đó \(x\inƯ\left(2\right)=\left\{1;2\right\}\)
Mà x > 8 nên \(x\in\varnothing\)
\(\text{Bài giải}\)
\(70\text{ ⋮ }x\) \(84\text{ ⋮ }x\) \(120\text{ ⋮ }x\)
\(\Rightarrow\text{ }x\inƯC\left(70\text{ , }84\text{ , }120\right)\)
\(\text{Ta có : }\)
\(70=2\cdot5\cdot7\)
\(84=2^2\cdot3\cdot7\)
\(120=2^3\cdot3\cdot5\)
\(\Rightarrow\text{ }ƯCLN\left(70\text{ , }84\text{ , }120\right)=2\)
\(\Rightarrow\text{ }ƯC\left(70\text{ , }84\text{ , }120\right)=Ư\left(2\right)=\left\{1\text{ ; }2\right\}\)
\(\text{Mà }x>8\text{ }\Rightarrow\text{ }x\in\varnothing\)
