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1^2-2^2+3^2-4^2+5^2-6^2+……+99^2-100^2的值是?四个选择A.5050B.-5050C.10100D,-10100
题目详情
1^2-2^2+3^2-4^2+5^2-6^2+……+99^2-100^2的值是?
四个选择
A.5050 B.-5050 C.10100 D,-10100
四个选择
A.5050 B.-5050 C.10100 D,-10100
▼优质解答
答案和解析
1^2-2^2+3^2-4^2+5^2-6^2+……+99^2-100^2
=(1+2)(1-2)+(3+4)(3-4)+.+(99+100)(99-100)
=-(1+2)-(3+4)-.-(99+100)
=-(1+2+3+4+...+99+100)
=-5050
选B
=(1+2)(1-2)+(3+4)(3-4)+.+(99+100)(99-100)
=-(1+2)-(3+4)-.-(99+100)
=-(1+2+3+4+...+99+100)
=-5050
选B
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