把每个式子减2,
(1)(1/17+1/19)×20 ,20/17+20/19-2=3/17+1/19
(2)(1/24+1/29)×30 ,30/24+30/29-2=6/24+1/29
(3)(1/31+1/37)×40 ,40/31+40/37-2=9/31+3/37
(4)(1/41+1/47)×50 ,50/41+50/47-2=9/41+3/47
观察可得(3)(4)分子相等,分母小的反而大.所以(3)》(4)
2可以变为9/36+3/87 看出2
把每个式子减2,
(1)(1/17+1/19)×20 ,20/17+20/19-2=3/17+1/19
(2)(1/24+1/29)×30 ,30/24+30/29-2=6/24+1/29
(3)(1/31+1/37)×40 ,40/31+40/37-2=9/31+3/37
(4)(1/41+1/47)×50 ,50/41+50/47-2=9/41+3/47
观察可得(3)(4)分子相等,分母小的反而大.所以(3)》(4)
2可以变为9/36+3/87 看出2