Question

Fie mulțimile:
A={x ∈ Z | -12/2x+1 ∈ N}
B={ x∈ Z | -18/2x+1 ∈ N}
Determinați elementele mulțimilor A si B.

Answer 1

a) -12/2x+1 € N rezulta 2x+1 € {-1, -2, -3, -4, -6, -12}
2x € {-2, -3, -4, -5, -7, -13}
x € Z rezulta x € {-1, -2}

b) 2x+1 € {-1, -2, -3, -6, -9, -18}
2x € {-2, -3, -4, -7, -10, -19}
x € {-1, -2, -5}

Answer 2

A = {x ∈ Z | -12/(2x + 1) ∈ N}
x ∈ {-1; -1,5; -2; -2,5; -3,5; -6,5}
A = {-1; -1,5; -2; -2,5; -3.5; -6,5}

B = {x ∈ Z | -18/(2x + 1) ∈ N}
x ∈ {-1; -1,5; -2; -3,5; -5; -9,5}
B = {-1; -1,5; -2; -3,5; -5; -9,5}