Thu gọn S = x0 + x1 + … + xn.
Giải thích
S = x0 + x1 + … + xn
S . x = x1 + x2 + … + xn+1
S.x – S = (x1 + x2 + … + xn+1) – (x0 + x1 + … + xn)
S (x–1) = xn+1 – x0
S = xn+1– x0x−1
S = xn+1– 1x−1 .
S = x0 + x1 + … + xn
S . x = x1 + x2 + … + xn+1
S.x – S = (x1 + x2 + … + xn+1) – (x0 + x1 + … + xn)
S (x–1) = xn+1 – x0
S = xn+1– x0x−1
S = xn+1– 1x−1 .