Question

[Tranminhanh]

(x+4) +(x+7) + .........+ (x+ 28 ) = 156

(x+2) + (x+4) + ( x +6 ) +........+ (x+ 1996 ) = 998000

11x (x-6 ) = 4 x x +11

x+2 x x + 3 x x +......+ 10 x x =165