Question

fie multimile A = {x apartine lui Z* / I2x+1I < 5}
                  B={x apartine lui Z / 15 supra x+3 apartine lui N}
aflati multimile 

Answer 1

1)-5 < | 2x+1| < 5

-5 <2x+1 < 5 |-1

-6 < 2x < 4 |:2

-3 < x < 2

A= { -2;-1;1}

2)$\frac{15}{x+3} \ apartine\ N \\ x \ apartine \ Z => (x+3)|15 <=> x+3= [1,3,5,15] \\ 1) x+3=1 =>x=1-3=-2 \\ 2)x+3=3 =>x=3-3=0 \\ 3)x+3=5 =>x=5-3=2 \\4)x+3=15 =>x=15-3=12 \\ B=[-2;0;2;12]$