Question

Determinati multimile:
A={x Ix ∈Z, I x+1I=4}
B={xI x ∈N,I 2-5xI=7}
C={xI x ∈Z,I 2x-3I=1}
D={xI x∈ N,3=I 5-xI }

Answer 1

|x+1|=4 si |x+1|=-4 

x+1=4  =>  x=3  
x+1=-4 => x=-5

|2-5x|=7 si |2-5x|=-7

2-5x=7  => -5x=5  => x=-1  
 2-5x=-7 => -5x=-9 x=9/5

|2x-3|=1 si |2x-3|=-1

2x-3=1 => 2x=4 => x=2  
 2x-3=-1 => 2x=2 => x=1

|5-x|=3 si |5-x|=-3

5-x=3 => x=2
5-x=-3 => -x=-8 => x=8

Sper ca ti-am fost de ajutor ! :)