Question

1.Numerele naturale x care verifică relatia (x+2)|(2x+7) sunt
a)0
b)1
c){1,2}
d){1,3}

Answer 1

(x+2) divide (2x+7)

(x+2) divide (2x+4)      (-)

(x+2) divide (2x+7-2x-4)

(x+2) divide 3 => x+2 ∈ {1, 3} si x∈N

x+2=1 => x=-1, nu convine

x+2=3  

=> x=1;  

R: b)