Question

Write the explicit formula for the

sequence below. Then, find the number
term in the sequence as listed.
140,130,120,110...

Answer 1

`a_n=-10n+150`

Explanation:

This is consider a linear pattern (arithmetic pattern).

We know this because it is either going up or down by the same number each time. It's going down by 10 in this case.

So -10 is the slope of this linear pattern.

The equation for a linear pattern is:

y=mx+b

where x represents the position the term is in

and

where y represents the actual term

and

where m is the slope

So we have y=-10x+b.

(x,y)

(term position in sequence, actual term)

(1,140)

(2,130)

(3,120)

(4,110)

We can find b by using a number with it's position in the sequence (that is plug in one of your points above).

y=-10x+b

140=-10(1)+b

140=-10+b

150=b (after adding 10 on both sides)

The explicit equation for the sequence is y=-10x+150.

They probably prefer you to write:
`a_n=-10n+150` instead.