<=> (1927-x/91 + 1)+(1925-x/93 + 1) + (1923-x/95 + 1) + (1921-x/97 + 1) = 0
<=> 2018-x/91 + 2018-x/93 + 2018-x/95 + 2018-x/97 = 0
<=> (2018-x).(1/91 + 1/93 + 1/95 + 1/97) = 0
<=> 2018-x = 0 ( vì 1/91 + 1/93 + 1/95 + 1/97 > 0 )
<=> x = 2018
Vậy x = 2018
Tk mk nha