a) Ư(10) = {-1: -2; -5; -10; 1; 2; 5; 10}
B(10) = {10k| k € Z}
b) Ư(15) = {-15; -5; -3; -1; 1; 3; 5; 15}
B(15) = {15k| k € Z}
c) Ư(-24) = {-24; -12; -8; -6; -4; -3; -2; -1; 1; 2; 3; 4; 6; 8; 12; 24}
B(-24) = {-24k| k € Z}
d) ƯC(-15; 20) = {-5; -1; 1; 5}
1a, ư(10): +-1,+-2,+-5,+-10 b(10): 10,20,30,40,50,....
b,ư(15): +-1,+-5,+-3,+-15 b(15): 15,30,45,60,75,....
c,ư(-24): +-1,+-24,+-4,+-6,+-12,+-2,+-3,+-8
b(-24): 24 nhân với x(x là số bất kì)
d,ưc(-15:20): +-5,+-1
Bài 2:
a: \(\Leftrightarrow n-1\in\left\{1;-1;7;-7\right\}\)
hay \(n\in\left\{2;0;8;-6\right\}\)
b: \(\Leftrightarrow2n-1\in\left\{1;-1;3;-3\right\}\)
hay \(n\in\left\{1;0;2;-1\right\}\)