Question

3/4-7/12+9/20-11/30+13/42-15/56简便计算

打错了，开始是4/3,之后没错

Answer 1

4/3-7/12+9/20-11/30+13/42-15/56
=(1+1/3)-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)
=1-1/8
=7/8

Answer 2

3/4-7/12+9/20-11/30+13/42-15/56
=3/4-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7-1/7-1/8
=3/4-1/3-1/8
=18/24-6/24-3/24
=3/8

4/3-7/12+9/20-11/30+13/42-15/56
=4/3-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7-1/7-1/8
=4/3-1/3-1/8
=1-1/8
=7/8