作业帮5/1+45/1+117/1+221/1=?
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5/1+45/1+117/1+221/1=?
5/1+45/1+117/1+221/1=?
5/1+45/1+117/1+221/1=?
1/5+1/45+1/117+1/221
=4×(1/5+1/45+1/117+1/221)÷4
=(4/5+4/45+4/117+4/221)÷4
=(1-1/5+1/5-1/9+1/9-1/13+1/13-1/17)÷4
=(1-1/17)÷4
=16/17÷4
=4/17
=17分之4
5/1+45/1+117/1+221/1=5+45+117+221=?50+338=388
388 ？？
=1/5+1/(5*9)+1/(9*13)+1/(13*17) =1/4*(1-1/5+1/5-1/9+1/9-1/13+1/13-1/17) =4/17