下面是2013年2月21日的SAT官方每日一题的内容，是关于数学方面的，题型是选择。SAT官方每日一题是collegeboard每天都会发布的题目，关于SAT考试的三个部分的各个题型。下面我们就一起来看一下这个SAT官方每日一题吧。

　　SAT官方每日一题之数学---选择：

　　Mathematics > Standard Multiple Choice

　　Read the following SAT test question and then click on a button to select your answer.

　　A florist buys roses ata piece and sells them fora piece. If there are no other expenses, how many roses must be sold in order to make a profit of?

　　(A)

　　(B)

　　(C)

　　(D)

　　(E)

　　The correct answer is E

　　Explanation

　　下面是一道和SAT官方每日一题相似的题目，供大家练习：

　　Each rose brings a profit ofminus, or. The number of roses that need to be sold to make a profit ofis. This isroses.

　　, , ,, ... 

　　The first four terms of a sequence are shown above. Which of the following could be the formula that gives the th term of this sequence for all positive integers ? 

　　Answer Choices

　　(A)  

　　(B)  

　　(C)  

　　(D)  

　　(E)  

　　The correct answer is E

　　Explanation

　　If a formula gives the th term of the sequence for all positive integers , it must give the th term of the sequence for . If , then and , but the first term of the sequence is , so the general formula cannot be or . Also, if , then and , but the third term of the sequence is , so the general formula cannot be or . However, for , the values of are , , , , respectively. Therefore, the general formula for this sequence could be .

　　以上就是关于2013年2月21日SAT官方每日一题中数学部分的详细内容，包括了题目和选项以及答案，后面附有一道相关的练习题。大家可以在备考SAT的过程中关注SAT每日一题的内容，这样就可以更好有不间断的练习，也就能在日积月累的过程中得到提高。