tinh nhanh tong : 2+4+6+....+100
Co the tinh nhanh tong 37+198 bang cach ap dung tinh chat ket hop cua phep cong
tinh nhanh tong
q= 2+4+6+.......+22
tinh nhanh tong sau:
S=1X6+2X7+3x8+4x9+...+100x105
S=1/2mu2 + 1/3mu2 + 1/4mu2 + ... + 1/100mu2 bé hơn 1
tinh nhanh cac tong sau
1+2+3+4+5+...+n
Tinh tong day so :1+2+3+..+20
nhanh len tick cho
chung minh rang : 1 +1/2mu2 +1/3mu2 +1/4mu2 +...+1/100mu2 < 2
tinh nhanh cac tong sau
1+2+3+4+5+....+n