Question

Fie multimile A={× apartine N / 4 mai mic decat ײ mai mic sau egal ca 121 }
B={× apartine N / 2× + 1 apartine D lui 15 }





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Answer 1

4<x²<121⇒2²<x²<11²⇒2=2=2⇒2<x<11⇒x∈N⇔x∈[3,4,5,6,7,8,9,10];
⇒A=[3,4,5,6,7,8,9,10];

2x+1∈D15⇔D15=[1,3,5,15];
⇒2x+1=1⇒2x=0⇒x=0;
⇒2x+1=3⇒2x=2⇒x=1;
⇒2x+1=5⇒2x=4⇒x=2;
⇒2x+1=15⇒2x=14⇒x=7;
⇒x∈[0,1,2,7];
⇒B=[0,1,2,7];