Question

Scrieti prin enumerare elementele multimii A={n€N|6<_2n+4<20}

Answer 1

A = {n∈N I 6≤2n+4<20}

6≤2n+4 => 2n ≥6-4 => 2n≥2 => n ≥1

2n+4<20 => 2n < 16 => n <8

n ∈ [1 ,8)

A ={ 1,2,3,4,5,6,7}

Answer 2

A={n € N | 6≤2n+4<20}

2n+4≥6

2n≥6-4

2n≥2

n≥1

2n+4<20

2n<20-4

2n<16

n<8

=>n € [1,8)

=>A={1,2,3,4,5,6,7}