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(1/11+1/21+1/31)x(1/21+1/31+1/41)-(1/11+1/21+1/31+1/41)x(1/21+1/31)怎么做.
题目详情
(1/11+1/21+1/31)x(1/21+1/31+1/41)-(1/11+1/21+1/31+1/41)x(1/21+1/31)怎么做.
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答案和解析
(1/11+1/21+1/31)x(1/21+1/31+1/41)-(1/11+1/21+1/31+1/41)x(1/21+1/31)
=(1/11+1/21+1/31)×(1/21+1/31) +(1/11+1/21+1/31)×(1/41)
-(1/11+1/21+1/31)×(1/21+1/31)-(1/41)×(1/21+1/31)
=(1/41)×(1/11+1/21+1/31)-(1/41)×(1/21+1/31)
=(1/41)×(1/11)
=1/451
=(1/11+1/21+1/31)×(1/21+1/31) +(1/11+1/21+1/31)×(1/41)
-(1/11+1/21+1/31)×(1/21+1/31)-(1/41)×(1/21+1/31)
=(1/41)×(1/11+1/21+1/31)-(1/41)×(1/21+1/31)
=(1/41)×(1/11)
=1/451
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