Bài 1:
\(12:\left\{390-\left[500-\left(125+35\cdot7\right)\right]\right\}\\ =12:\left\{390-\left[500-\left(125+245\right)\right]\right\}\\ =12:\left\{390-\left[500-370\right]\right\}\\ =12:\left\{390-130\right\}\\ =12:260\\ =\frac{3}{65}\)
Bài 2:
a) \(6+n⋮n\)
Có: \(n⋮n\)
\(\Rightarrow6+n-n⋮n\\ \Rightarrow6⋮n\\ \Rightarrow n\in\left\{1;2;3;6\right\}\)
Vậy \(n\in\left\{1;2;3;6\right\}\)
b) \(3n+2⋮n\)
Có \(3n⋮n\)
\(\Rightarrow3n+2-3n⋮n\\ \Rightarrow2⋮n\\ \Rightarrow n\in\left\{1;2\right\}\)
Vậy \(n\in\left\{1;2\right\}\)
Bài 1:
\(12:\left\{390-\left[500-\left(125+35.7\right)\right]\right\}\)
\(=12:\left\{390-\left[500-370\right]\right\}\)
\(=12:\left\{390-130\right\}\)
\(=12:260\)
\(=\frac{3}{65}.\)
Chúc bạn học tốt!
Bài 1:
12:{390−[500−(125+35.7)]}12:{390−[500−(125+35.7)]}
=12:{390−[500−370]}=12:{390−[500−370]}
=12:{390−130}=12:{390−130}
=12:260=12:260
=365.=365.
Chúc bạn học tốt!
