简算:
1.(19/20)+(29/30)+(41/42)+(55/56)
解,得:
==(1-1/20)+(1-1/30)+(1-1/42)+(1-1/56)
==4-1/20-1/30-1/42-1/56
==4-(1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8)
==4(1/4-1/8)
==4*(1/8)
==1/2
简算:
1.(19/20)+(29/30)+(41/42)+(55/56)
解,得:
==(1-1/20)+(1-1/30)+(1-1/42)+(1-1/56)
==4-1/20-1/30-1/42-1/56
==4-(1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8)
==4(1/4-1/8)
==4*(1/8)
==1/2