14+2345+234+234*几等于 3

问题描述:

14+2345+234+234*几等于 3

(3-14-2345-234)/234=-1295/117

x=-2590/234

14+2345+234+234x=3
2593+234x=3
234x=3-2593
234x=-2590
x=-2590/234

1+2-3-4+5+6-7-8+…+1997+1998-1999-2000+2001+2002-2003-2004+2005
=(2005-2004-2003+2002)+(2001-2000-1999+1998)+…+(5-4-3+2)+1
=0+0+0+…+1=1
(2+23+234)*(23+234+2345)-(2+23+234+2345)*(23+234)
=(2+23+234)·(23+234)+(2+23+234)·2345-(2+23+234)·(23+234)-2345·(23+234)
=(2+23+234)·2345-2345·(23+234)
=2·2345+(23+234)·2345-2345·(23+234)
=4690