c) x -1/2 -1/6 -1/12 -1/20 = 1/30
Giải thích
c) x−12−16−112−120=130x=12+16+112+120+130x=12+12.3+13.4+14.5+15.6x=12+12−13+13−14+14−15+15−16x=12+12−16x=1−16x=56Vậy x=56
c) x−12−16−112−120=130x=12+16+112+120+130x=12+12.3+13.4+14.5+15.6x=12+12−13+13−14+14−15+15−16x=12+12−16x=1−16x=56Vậy x=56