Consider the arithmetic sequence.

-9, -2, 5, 12, . . .

Given that the sequence is represented by the function f(n), what are the values of f(1) and the common difference?

A.
f(1) = -2
Common difference : 7
B.
f(1) = -9
Common difference : -7
C.
f(1) = -2
Common difference : -7
D.
f(1) = -9

Cis your correct answer

You just divide and you will find x

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.