Woah. who understands this? help!!?

Question

6) The first term and common ratio of a geometric sequence is given below. What are the first five terms of the sequence?

7) In an arithmetic sequence, the twenty-fifth term is 6,275 and the common difference is 250. What is the first term?

[[LOOK AT THIS]] both are on here

http://s218.photobucket.com/albums/cc35/stephanielazar1992/?action=view&current=untitled-18.jpg

Answer 1

6) Using this symbol _ to denote subs we have:

     a_1=5, r=-4

     a_n=(a_1)r^(n-1)

Substitute

a_n=(5)(-4)^(n-1)

we can use this formula to find the rest of the terms by simply substituting in the values we want

a_1=5 (given)

a_2=(5)(-4)^(2-1)

=5(-4)^1

=5(-4)

=-20

There are the first two terms continue using the above equation and substitute the values in to find the other three.

You should be able to solve #7 using a similar method. Just substitute in and solve.

  

Answer 2

6) 5, -20.....

i need paper haha