離散+線代

大家好:

想問兩個問題

題一:

98交大資訊

Let a, and b be two symbols. The natation a³ denotes the

string aaa, that is, a string of three a's. Similarly, the notation a⁴ denotes

the string of four a's. Similarly, the notation a^k denotes the string of k a's.

Find a 1-1 mapping from N to {a^kb^lk | j, k∈N).

想了好久不知道要怎麼定義函數

題二:

98中正電機

(a)if Ax=b is any consistent linear system of m equations in n unknows,then the solution set is a subspace of Rⁿ

^{這個選項是錯的}

^{想問一下是錯在不是subspace嗎}

^{我的想法:}

^{因為是any consistent}

^{所以當b不等於o時 若把x代o Ax不會對應到o =>不為子空間}

這想法是對的嗎?

原本是覺得錯在Rⁿ

^{後來發現解集合好像都在}Rⁿ

謝謝: )