Solution.
(a) Knowing that ∣x∣+∣y∣⩾∣x−y∣⟹∣a+b∣+∣a+c∣⩾∣a+b−a−c∣=∣b−c∣. (2p)
(b) Applying, in turn, the relation shown in (a), we obtain
∣x+1∣+∣x+2014∣∣x+2∣+∣x+2013∣……………………………………………⩾∣x+2014−x−1∣=2013⩾∣x+2013−x−2∣=2011⋯⋯+…+1008−x−1007∣=1
Summing the inequalities, we obtain:
∣x+1∣+∣x+2∣+…+∣x+2014∣⩾1+3+…+2011+2013=10072
where
1+3+…+2011+2013=(1+2+…+2014)−(2+4+…+2014)=22014⋅2015−221007⋅1008=10072