12又3/4÷1又1/5+5.25×5/6=?139×137/138+137×1又1/138=?_数学解答

12又3/4÷1又1/5+5.25×5/6=?
139×137/138+137×1又1/138=?

人气：478 ℃　时间：2019-08-31 14:36:46

解答

=139x137/138+137x139/138
=139x137x2/138
=(138+1)(138-1)x2/138
=(138-1/138)x2
=276-1/69