1*3/11+3*5/11+5*7/11.97*99/11题怎么做?11/1*3+11/3*5+11/5*7......11/97*99题怎么做?

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1*3/11+3*5/11+5*7/11.97*99/11题怎么做?11/1*3+11/3*5+11/5*7......11/97*99题怎么做?

1*3/11+3*5/11+5*7/11.97*99/11题怎么做?11/1*3+11/3*5+11/5*7......11/97*99题怎么做?
1*3/11+3*5/11+5*7/11.97*99/11题怎么做?
11/1*3+11/3*5+11/5*7......11/97*99题怎么做?

1*3/11+3*5/11+5*7/11.97*99/11题怎么做?11/1*3+11/3*5+11/5*7......11/97*99题怎么做?
1*3/11+3*5/11+5*7/11.97*99/11
=11*(1-3/1+3/1-5/1+6/1-7/1+……+97/1-99/1)÷2
=11*(1-99/1)÷2
=11*99/49
=9/49