Question

Aflati numereloe naturale X , astfel incat 2X + 3 sa se divida cu 15 si X < 36

Answer 1

2x+3 =0 => x= -3/2 ,dar x natural => nu este bun
2x+3=15=> x=(15-3)/2 =12/2=6
2x+3=30=> x=(30-3)/2 =27/2 => nu est bun
2x+3=45 => x=(45-3)/2=42/2=21
2x+3=60=> x=(60-3)/2=57/2 => nu este bun
2x+3=75=> x=(75-3)/2 =72/2= 36 ,dar x < 36 => singurele solutii sunt
6 si 21

Answer 2

M15={0,15,30,45,60,75,....}
x<36
2x+3=15
2x=15-3
2x=12
x=12:2
x=6
2x+3=45
2x=45-3
2x=42
x=42:2
x=21
x={6,21}