求助OG 12的一道数学题翻译

amyvigil

228题： An arithmetic sequence is a sequence in which each term after the first is equal to the sum of the preceding term and a constant. If the list of letters shown above is an arithmetic sequence, which of the following must also be an arithmetic sequence? Sequence: p,r,s,t,u
1. 2p,2r,2s,2t,2u
2. p-3,r-3,s-3,t-3,u-3

按照OG的解释，翻译这句话p,r,s,t,u是等差数列，p-r=t-s=u-t。可我怎么都看不出来原文的意思是等差数列，理解应该是每个数等于之前数的相加和，求高人指点，谢谢！

393075583

An arithmetic sequence is a sequence in which each term after the first is equal to the sum of the preceding term and a constant. If the list of letters shown above is an arithmetic sequence, which of the following must also be an arithmetic sequence? Sequence: p,r,s,t,u

每个数 等于它前面的数加上一个常数
An=A（n-1）+d

这是等差数列

amyvigil

噢！！恍然大悟，谢谢谢谢~~~