两个问题

lnlynn

1。X=Y+10
   X大于（Y+10）
这两个表达式英文如何表示？

2。一堆球，各种颜色，求有多少种取法，若不放回可用组合数算，若放回是不是就不能用组合数算了？[em08][em08][em08]

abelianrose

若放回, you need not the use the combinatorics . Cause everytime you pick one
ball from N balls, there are still N choices avaliable(unless there is some restriction). You can simply multiple the numbers.

lnlynn

thank you,abelianrose!
can anyone answer my first question,i am very nervous,i will test next monday!