Write the following Arithmetic Sequence using an Explicit Formula: a1 = 12, an = an-1 – 3

the answer is "add 2y and y"

step-by-step explanation:

you need to collect the like terms first.

step-by-step explanation:

let pq = qr = rs = x, and xz = y and zu = z.

if the horizontal lines are parallel, then corresponding segments are in proportion:

substitute:

therefore 3 = y = z.

xu = y + z → xu = 3 + 3 = 6