用简便方法计算1-2²+3²-4²+5²-6²+······+99²-100²
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用简便方法计算卜运1-2²+3²-4²+5²-6²+······+99²-100²
解:原式=(3²-2²)+(5²-4²型亩梁)耐猜+........+(99²-98²)+1-100²
=(3-2)×(3+2)+(5-4)×(5+4)+........+(99-98)(99+98)+1-100²
=5+9+...+197+1-100²
=(197+5)×49÷2+1-100²
=101×49+1-10000
=(100+1)×49+1-10000
=4949+1-10000
=-5050
解:原式=(3²-2²)+(5²-4²型亩梁)耐猜+........+(99²-98²)+1-100²
=(3-2)×(3+2)+(5-4)×(5+4)+........+(99-98)(99+98)+1-100²
=5+9+...+197+1-100²
=(197+5)×49÷2+1-100²
=101×49+1-10000
=(100+1)×49+1-10000
=4949+1-10000
=-5050
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