( X + 1 ) + ( X + 4 ) + ( X + 7 ) + ( X + 10) + ....+ ( X + 28 ) = 155...

bài 10 : - HE THONG DE THI HSG 4
Lớp 4 HE THONG DE THI HSG 4

Bài 10 : Tìm X : ( X + 1 ) + ( X + 4 ) + ( X + 7 ) + ( X + 10) + ....+ ( X + 28 ) = 155 .

Đ/S:...