c. 28 + 20x =248 + 2x ; 20x - 2x = 248 -28 ; 18x = 220
x = 220 /18 =110 /9
1. 1 +x+2+y = multiplu de cu x, y = in baza 10 sunt
x ,y =0,1,2,3,4,5,6,7,8,9
3 + x+y ∈M ₃ daca x =0 , y=0 1020
x=0 ,y=3 1023
x =3 , y=0 1320
x=1 , y=2 1122
x=2 , y=1 1221
x=1 y=5 1125
x =2 y =4 1224
x =3 y=3 1323
1521 ; 1422 ;
2. n +1 2
25 = 25 daca n +1 = 2 ; n=1
3 .
n n n
6 + 6 · 6 = 252 ; 6 · ( 1 + 6 ) = 252
n 2
6 =252 : 7 = 36 = 6 ⇒ n =2
