2分之1+6分之1+加12分之1+20分之1+30分之1+42分之一等于几
问题描述：
2分之1+6分之1+加12分之1+20分之1+30分之1+42分之一等于几
答
1/2+1/6+1/12+1/20+1/30+1/42=6/12+2/12+1/12+3/60+2/60+1/42
=9/12+5/60+1/42
=45/60+5/60+1/42
=50/60+1/42
=5/6+1/42
=35/42+1/42
=36/42
=6/7
答
列项相加 等于1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=6/7
答
你好,寒风烁烁
1/2+1/6+1/12+1/20+1/30+1/42
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7