数学题,帮帮忙~~~~~
来源:百度知道 编辑:UC知道 时间:2024/05/15 16:55:29
简算(必须用简便方法)
(1)19*(98/99)=?
(2)(67+2/7)*(7/9)=?
(1)19*(98/99)=?
(2)(67+2/7)*(7/9)=?
简算(必须用简便方法)
(1)19*(98/99)
=19*[1-1/99]
=19-19/99
=18+[1-19/99]
=18+80/99
=18又80/99
(2)(67+2/7)*(7/9)=?
=67*7/9+2/7*7/9
=[63+4]*7/9+2/9
=63*7/9+4*7/9+2/9
=49+28/9+2/9
=49+30/9
=49+3+1/3
=52又1/3
大哥,题太难啊
1.19*(98/99)=19*(1-(1/99)) =19-(19/99)=1892/99
2.(67+2/7)*(7/9)=67*(7/9)+(2/7)*(7/9)=(469/9)+(2/9)=471/9