GRE
The number of ordered pairs (x, y) in S such that x=y
16
The number of ordered triples ($$x_1$$, $$x_2$$, $$x_3$$), where $$x_1$$, $$x_2$$ and $$x_3$$ are non-negative integers such that $$x_1$$+$$x_2$$+$$x_3$$=9
55
p
1-p
2p
$$p^{2}$$
k
1-x
25000 +道题目
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