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当n=1时,原式的值为1+2+22+23+24=31,当n=k时,原式=1+2+22+…+25k-1当n=k+1时,原式=1+2+22+…+25k+4∴从k到k+1时需增添的项是 25k+25k+1+25k+2+25k+3+25k+4故填:32 25k+25k+1+25k+2+25k+3+25k+4