1^2+2^2+3^2+……+N^2=1/6n(n+1)(2n+1),试求2^2+4^2+6^2+……+50^2的值
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1^2+2^2+3^2+……+N^2=1/6n(n+1)(2n+1),试求2^2+4^2+6^2+……+50^2的值
2^2+4^2+6^2+……+50^2
=2^2(1^2+2^2+3^2+.+25^2)
=4*1/6*25*(25+1)(2*25+1)
=25*26*51*2/3
=25*26*17*2
=22100
=2^2(1^2+2^2+3^2+.+25^2)
=4*1/6*25*(25+1)(2*25+1)
=25*26*51*2/3
=25*26*17*2
=22100
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