Question Number 115072 by A8;15: last updated on 23/Sep/20
Commented by A8;15: last updated on 23/Sep/20
please help with the solution
Answered by 1549442205PVT last updated on 23/Sep/20
$$\mathrm{Opening}\:\mathrm{brackets}\:\mathrm{we}\:\mathrm{get} \\ $$$$\mathrm{S}=\mathrm{2020}−\left(\mathrm{2019}−\left(\mathrm{2018}−\left(\mathrm{2017}−\right.\right.\right. \\ $$$$\left(\mathrm{2016}−\left(....\left(\mathrm{2}−\mathrm{1}\right)...\right)\right. \\ $$$$=\mathrm{2020}−\mathrm{2019}+\mathrm{2018}−\mathrm{2017}+... \\ $$$$+\mathrm{2}−\mathrm{1}=\left(\mathrm{2020}−\mathrm{2019}\right)+\left(\mathrm{2018}−\mathrm{2017}\right)+ \\ $$$$+...+\left(\mathrm{2}−\mathrm{1}\right)=\mathrm{1}+\mathrm{1}+...+\mathrm{1}=\mathrm{1010} \\ $$$$\left(\mathrm{Since}\:\mathrm{all}\:\mathrm{2020}\:\mathrm{terms}\Rightarrow\mathrm{1010}\:\mathrm{sums}\right) \\ $$
Commented by A8;15: last updated on 23/Sep/20
thank you sir
Answered by JDamian last updated on 23/Sep/20
$$\left.{d}\right)\:\mathrm{1010} \\ $$
Commented by A8;15: last updated on 23/Sep/20
how ? I need a solution