Question

Determinati x € N* pentru care: 1 supra 10<10 supra x<1 supra 9

Answer 1

1/10 < 10/x<1/9 (inversam fractiile si schimbam ordinea)
9/1 < x/10 < 10/1  /*10
90<x<100
x={91,92,93,94,95,96,97,99,99}