An = 7n-1 for 1 ≦ n ≦ 4
is short for these instructions:
1. Substitute 1 for n into 7n-1 and simplify what you get.
2. Write that down with a comma after it.
3. Substitute 2 for n into 7n-1 and simplify what you get.
4. Write that down next to the comma that you wrote in step 2, and put a comma
after that.
5. Substitute 3 for n into 7n-1 and simplify what you get.
6. Write that down next to the comma that you wrote in step 4, and put a comma
after that.
7. Substitute 4 for n into 7n-1 and simplify what you get.
8. Write that down next to the comma that you wrote in step 6, but don't put a
comma after that because you are done.
Now let's do that:
1. Substitute 1 for n into 7n-1 and simplify what you get.
7(1)-1 = 7-1 = 6
2. Write that down with a comma after it.
6,
3. Substitute 2 for n into 7n-1 and simplify what you get.
7(2)-1 = 14-1 = 13
4. Write that down next to the comma that you wrote in step 2, and put a comma
after that.
6, 13,
5. Substitute 3 for n into 7n-1 and simplify what you get.
7(3)-1 = 21-1 = 20
6. Write that down next to the comma that you wrote in step 4, and put a comma
after that.
6, 13, 20,
7. Substitute 4 for n into 7n-1 and simplify what you get.
7(4)-1 = 28-1 = 27
8. Write that down next to the comma that you wrote in step 6, but don't put a
comma after that because you are done.
6, 13, 20, 27
That list is the answer.
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Note that:
A1 = 6, A2 = 13, A3 = 20, A4 = 27.
The 1 ≦ n ≦ 4 tells you to substitute for n all the integers from
1 to 4, inclusive, into An = 7n-1.
Edwin
