Question

Please help
3. Write an explicit formula for the sequence -4, 1, 6, 11....

Answer 1

Take a look at that site. It is cool and interesting!

http://www.mathwords.com/e/explicit_formula.htm

Answer 2

Try to find the solution in the form
\[
a_n= c\ n + b
\]
Use the information you have find c and d

Answer 3

You know that
\[
a_1=c+b=-5
\]
What else do you know?

Answer 4

You also know that
\[
a_n = a_{n-1}+5
\]
You this to find another relation between c and b

Answer 5

Then solve for c and b and you will be done

Answer 6

Let me know when you come back