Question

Determina nr prime a,b care verifica relatia : 3x a + 2x b = 16

Answer 1

3a=16-2b⇒3a=2(8-b)⇒3a(nr par)⇒a=nr par
nr par prim=2⇒a=2
4+2b=16
2b=10
b=5
numerele prime sunt:a=2
b=5

Answer 2

numere prime 2,3,5,7...
a=2, 6+2b=16, 2b=10, b=5   a=2, b=5
a=3, 9+2b=16, 2b=7,  nu e numar prim
a=5, 15+2b=16, 2b=1,nu e numar prim
a=7, 21+2b=16 , 2b=-5 nu e numar prim
pentru numere>7 verificarea nu mai are sens deoarece se obtin numere negative