Question

(x + 1) + (x + 3) + (x + 5) + (x + 7) + . . . + (x + 2015) = 1023120

x =

Answer 1

Số dấu ngoặc = (2015 - 1):2 +1 = 1008

=> 1008x +(2015+ 1).1008:2 = 1023120

=> 1008x   +  1008.1008 = 1008.1015

=> x +1008 = 1015

  x = 7