Question

17. Determinați elementele mulțimilor:
A = {x€N[3<√x<6};
C={x € N|27<3r<147};
B = {x € N |-55-√√x≤-2};
D = {x € Z | 15 ≤ x² ≤ 49}.
& Determinati elementele multimilor:

Answer 1

1. x∈N

3<√x<6 |² => 9<x<36

A={10,11,12,...,35}

2. x∈N

-5≤-√x≤-2 |•-1 => 5≤√x≤2 |² => 25≤x≤4

x≥25

x≤4 => B=Ø

3. x∈N

27≤3x²≤147 |÷3 => 9≤x²≤49 | ^1/2 => 3≤x≤7

C={3,4,5,6,7}

4. x∈Z

15≤x²≤49 | ^1/2 => √15≤x≤7

√15<√16 <=> √15<4

√15<√16 <=> -√15>-4

√15<√25 <=> √15<5

√15<√25 <=> -√15>-5

=> √15<n, √15>-n, n≥4

D={4,5,6,7}