Question

Determinati elementele multimii :

A={x∈Z stelat / Ix²-1I*(9-I2x-5I)>0}

Answer 1

|x²-1|>0∀x∈Z*\{-1;1} ptca e moduil sise anuleaza  pt x²-1=0; (x-1) (x+1)=0
9-|2x-5|>0
9>|2x-5|
|2x-5|<9
-9 <2x-5<9  | +5
-4<2x<14  |:2

-2<x<7

(-2;7)∩Z*\{-1'1}={2;3;4;5;6}