Find the thirty-second term of the following sequence. 9, 15, 21,
which of the following equations is of a parabola with a vertex at (0, 6)?

Let starting term, a = 9
Also let a = 
So,  = 9
= 15
= 21
-  = 6
-  = 6
∴ this is an arithmetic sequence.

We need to formulate a rule of the form:
= a + (n - 1)d
where n = the  term

So, let n = 32
= 9 + (32 - 1)6
= 9 + 31 x 6
= 9 + 186
= 195

If I have calculated correctly, the 32nd term shoud be 195.

Hope this ; )