Question

A= {x| x € N, 7< 5x + 2<17}.

Answer 1

7 < 5x+2 < 17 scazi inecuatia cu 2

7-2 < 5x+2-2 < 17-2

5 < 5x < 15 imparti inecuatia cu 5

1 < x < 3

x apartine (1,3) de unde x este numar natural

A = {2}

Answer 2

Răspuns:

7< 5x + 2<17

7 < 5x+2

7-2 < 5x

x > 5:5

x > 1

5x+2 < 17

5x < 17-2

x < 15:5

x < 3

x ∈ { 2 }