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Cardinalul multimii A={x ∈ Z | 16 < x² ≤ 100} este... .



Răspuns :

16 < x² ≤ 100

√16 < √x²  ≤  √100

4 < |x| ≤ 10

4 < x ≤10  => x∈ (4;10]  ∨  x∈{5,6,7,8,9,10}

A={5,6,7,8,9,10}

card A=6
16<x^2≥100
x∈(5,6,7,8,9,10)=>cardinalul multimii este 6
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