x(1+1/2+1/3+1/4+....+1/2019)=2019-1/2-2/3-3/4-....-2018/2019
in partea dreapta il scriem pe 2019 ca suma de 2019 de 1
2019-1/2-2/3-3/4-....-2018/2019=
=1+(1-1/2)+(1-2/3)+(1-3/4)+….+(1-2018/2019)
=1+1/2+1/3+1/4+…..+1/2019
=> x(1+1/2+1/3+1/4+....+1/2019)= 1+1/2+1/3+1/4+…..+1/2019
x=1
