Question

aflați câte numere de forma 7x3y sunt divizibile cu 2 , cu 5, cu10

Answer 1

7x3y este divizibil cu : 
a) 2 =>y∈{0,2,4,6,8}=>x∈{0,1,2,3,4,5,6,7,8,9}
Numerele sunt:
7030,7130,7230,7330,7430,7530,7630,7830,7930
7032,7132,7332,7432,7532,7632,7832,7932
7034,7134,7234,7334,7534,7634,7834,7934
7036,7136,7236,7336,7436,7536,7836,7936
7038,7138,7238,7338,7438,7538,7638,7938


b)5 =>y∈{0,5}=>x∈{0,1,2,3,4,5,6,7,8,9}
Numerele sunt: 7130,7230,7330,7430,7530,7630,7730,7830,7930,7035,7135,7235,7335,7435,7635,7735,7835,7935


c)10 =>y=0=>x∈{0,1,2,3,4,5,6,7,8,9}
Numerele sunt:
7130,7230,7330,7430,7530,7630,7730,7830,7930