1 < 4ˣ < 110
Vom separa in doua inegalitati
4ˣ > 1 => 4ˣ > 4⁰ => x > 0
4ˣ < 110 =>
=>x < 1/2*log2 (110) => x < 1/2* log(2*55) => x < 1/2*(log2 (2) + log2 (55)) =>
x < 1/2(1 + log2 (55)) => x < 1/2+ 1/2* log2 (55) si toata relatia e aprox 3,39...
Deci x apartine (0, 1/2+ 1/2* log2 (55))
Dar x apartine N => A = {1,2,3}
Cardinalul lui A este 3
