怎么算这个啊100²-99²+98²+97²···+4²-3²+2²-1²
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怎么算这个啊100²-99²+98²+97²···+4²-3²+2²-1²
怎么算这个啊100²-99²+98²+97²···+4²-3²+2²-1²
怎么算这个啊100²-99²+98²+97²···+4²-3²+2²-1²
100²-99²+98²+97²···+4²-3²+2²-1²
=(100+99)(100-99)+(98+97)(98-97)+.+(4+3)(4-3)+(2+1)(2-1)
=100+99+98+.+4+3+2+1
=(100+1)*100/2
=5050
98的平方后面是加还是减?
100²-99²+98²+97²···+4²-3²+2²-1²
=(100-99)(100+99)+(98-97)(98+97)+(96-95)(96+95)+-----+(4-3)(4+3)+(2-1)(2+1)
=199+195+191+187+-----+7+3
=(199+3)x50/2
=5050