Sets and sequences are another section of the SAT exam that many people have difficulties with, although this should not be the case. We are going to look at sets and sequences so that the overall math score on the SAT can be improved.
Sets
On the SAT math section, sets deal with union and intersection. The numbers that are in a set will often be called elements - or members of a set.
- A union is asked for with the symbol ∪ and refers to all numbers within the sets
- An intersection is asked for with the symbol ∩ and refers to only the numbers that are shared by both sets.
TIP: A good way to remember which is which is to think of the union symbol as a wide U and the intersection as a wide n. These types of questions do not show up often on the SAT and when they do they are not that difficult as long as test takers don't get confused by the symbols.
Sequences
Sequences are also pattern problems that can vary from simple to complex geometric sequences. For the simplest type, the test taker is usually asked to follow certain steps to get the next number. Knowing what a term is - a number or expression in the list - preceding (before) and subsequent (following.)
TIP: Follow the rules as they are written and not how they appear. For example, the second term in a particular sequence may be two times the first term, but this may not be how the sequence is being determined in the question.
Arithmetic and Geometric Sequences
More difficult sequence problems will ask a test taker to carry out a sequence for quite a long time. These sound and look simple, but they take a bit of time to do correctly if they are done in the traditional method. There are actually two ways to do these types of questions.
- Follow the directions and write out the sequence until the answer is achieved
- Memorize two sequence forumlas
For those not good at memorizing formulas, it is a better idea to skip sequence questions in order to get a higher math score on the SAT.
An arithmetic sequence is one where each subsequent number is a certain number plus or minus the previous number.
If you are not good at memorizing, you may want to skip sequence questions! It doesn't matter that the math is easy; sequence questions are often there simply to waste your time. If you can't remember the formula that goes with them, you're most likely better off skipping these questions and only coming back if you have the time to spend.
So here are the formulas:
You may also be asked to find the sum of a certain number of terms in an arithmetic sequence. In that case, you will need both the formula above, to find the term they're asking about, as well as another formula.
