Question

a) Calculati :  (-3) + (-2) + (-1)+ ......+(+25) + (+26) + (+27)
b)Daca |2z-1|=3  si z ∈ Z , atunci z ∈ {...........}

Answer 1

a) -3-2-1+0+1+2+3+4....+25=   4+5+6+...+25

=(4+25)*20/2= 29*10= 290

b) |2z-1|=3

2z-1= 3    2z-1 = -3
2z= 4         2z = -2
z= 2            z= -1