All GRE Math Resources
Example Questions
Example Question #3 : Nth Term Of An Arithmetic Sequence
The sequence is defined by:
What is the value of ?
Possible Answers:
Correct answer:
Explanation:
For this problem, you definitely do not want to "count upwards" to the full value of the sequence. Therefore, the best approach is to consider the general pattern that arises from the general definition:
This means that for every element in the list, each one is less than the one preceding it. For instance:
Now, notice that the first element is:
The second is:
The third could be represented as:
And so forth...
Now, notice that for the third element, there are only two instances of . We could rewrite our sequence:
This value will always "lag behind" by one. Therefore, for the th element, you will have:
All GRE Math Resources
Popular Subjects
Calculus Tutors in San Diego, French Tutors in New York City, ISEE Tutors in New York City, Chemistry Tutors in Los Angeles, ISEE Tutors in Atlanta, ISEE Tutors in Los Angeles, Statistics Tutors in Phoenix, Physics Tutors in Dallas Fort Worth, Math Tutors in San Diego, Math Tutors in Philadelphia
Popular Courses & Classes
ACT Courses & Classes in Philadelphia, Spanish Courses & Classes in Philadelphia, GRE Courses & Classes in Atlanta, Spanish Courses & Classes in San Diego, ISEE Courses & Classes in Miami, GMAT Courses & Classes in San Francisco-Bay Area, Spanish Courses & Classes in San Francisco-Bay Area, MCAT Courses & Classes in Houston, MCAT Courses & Classes in Los Angeles, ISEE Courses & Classes in Houston