Question

分数数学简便运算：4/5× 2/3+ 1/5÷ 3/4=？ 1/4× 5/7+ 1/4÷7/2+ 1/4=?

Answer 1

4/5×2/3+1/5÷3/4
=4/5×2/3+1/5×4/3
=4/5×(2/3+1/3)
=4/5

1/4×5/7+1/4÷7/2+1/4
=1/4×5/7+1/4×2/7+1/4
=1/4×(5/7+2/7+1)
=1/4×2
=1/2

Answer 2

4/5× 2/3+ 1/5÷ 3/4
=4/5×2/3+1/5×4/3
=4/5×2/3+4/5×1/3
=4/5×（2/3+1/3）
=4/5
1/4× 5/7+ 1/4÷7/2+ 1/4
=1/4×5/7+1/4×2/7+1/4
=1/4×（5/7+2/7+1）
=1/4×1
=1/4

追问

（5/7+2/7+1）
你加1了么。。

追答

4/5× 2/3+ 1/5÷ 3/4
=4/5×2/3+1/5×4/3
=4/5×2/3+4/5×1/3
=4/5×（2/3+1/3）
=4/5
1/4× 5/7+ 1/4÷7/2+ 1/4
=1/4×5/7+1/4×2/7+1/4
=1/4×（5/7+2/7+1）
=1/4×2
=1/2

Answer 3

4/5× 2/3+ 1/5÷ 3/4
=4/5× 2/3+ 1/5× 4/3
=8/15+4/15
=12/15
1/4× 5/7+ 1/4÷7/2+ 1/4
=1/4× 5/7+ 1/4×2/7+ 1/4
=5/28+2/28+1/4
=(5+2+7)/28
=14/28
=1/2

Answer 4

8/15+4/15=12/15=4/5
5/28+2/28=7/28=1/4