(2017 - x)³ + (2019 - x)³ + (2x - 4036)³ = 0
Đặt 2017-x là a; 2019 - x là b; 2x - 4036là c
do a+b+c=0
⇒ a+b= -c
⇔(a+b)³= (-c)³
có a³+b³+c³ = (a+b)³ -3ab(a+b) +c³= (-c) -3ab(-c) +c³=3abc
Do (2017 - x)³ + (2019 - x)³ + (2x - 4036)³ =0
⇒ 3(2017 - x)³ (2019 - x)³ (2x - 4036)³=0
⇒ 2017-x=0 ⇒ x= 2017
2019-x=0 ⇒x=2019
2x-4036=0⇒ x=2018