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

9. - DE THI VA DAP AN HSG TOAN LOP 5
Lớp 5 Toán DE THI VA DAP AN HSG TOAN LOP 5

9. Tỡm x:

(x + 1) + (x + 4) +(x + 7) +(x + 10) + … + (x + 28) = 155