第1个回答 2009-12-28
1,4/63+5/63=9/63=1/7
2,24/99+20/99=44/99=4/9
3,4/9*68/5+23/3*9/4=272/45+207/12=4193/45
第2个回答 2009-12-28
(4/7)*(1/9)+(5/9)/7
=4/(7*9)+5/(9*7)
=(4+5)/(9*7)
=9/(9*7)
=1/7
(4/9)*(6/11)+(5/9)*(4/11)
=(4/9)*(6/11)+(5*4)/(9*11)
=(4/9)*(6/11)+(5/11)*(4/9)
=(4/9)*(6/11+5/11)
=4/9
(4/9)*(12 5/8)+(5 3/8)/(2 1/4)
=(4/9)*(12 5/8)+(5 3/8)/(9/4)
=(4/9)*(12 5/8)+(5 3/8)*(4/9)
=(4/9)*(12 5/8+5 3/8)
=(4/9)*18
=8
第3个回答 2009-12-28
4/7×1/9+5/9÷7
=1/7×4/9+5/9×1/7
=1/7×(4/9+5/9)
=1/7×1
1/7
4/9×6/11+5/9×4/11
=6/9×4/11+5/9×4/11
=(6/9+5/9)×4/11
=1×4/11
=4/11
4/9×12 5/8+5 3/8÷2 1/4
=4/9×12 5/8+5 3/8÷9/4
=4/9×12 5/8+5 3/8×4/9
=4/9×(12 5/8+5 3/8)
=4/9×18
=8
好好学习,这么简单都不会,你几年级了