Find the 25th term of the following sequence: 20, 18, 16... Show all work
a^n = a^1 + (n - 1)d

Question

Find the 25th term of the following sequence: 20, 18, 16... Show all work
a^n = a^1 + (n - 1)d

anonymous · Answer

@kirbykirby @vlltimelow @amistre64 @abb0t @quickstudent @ganeshie8 Please help me out with this. I also have a couple more questions.

amistre64 · Answer

is that a subn,  or a to the nth power?

anonymous · Answer

subn, sorry I didn't clarify that.

amistre64 · Answer

since a1 is given, and n is given,  all thats required is to find d

amistre64 · Answer

20+d = 18
18+d = 16

etc ...

kirbykirby · Answer

$a_{25}=a_1+(25-1)d$
Here, $a_1$ is the first term, 20

Now, $d$ is the common difference between consecutive terms... i.e.
18 - 20 = -2 = d
16 - 18 = -2 = d

anonymous · Answer

That's what the formula looks like by the way

anonymous · Answer

So what would I do now?

amistre64 · Answer

determine the value of the 25th term of course

kirbykirby · Answer

replace $a_1$ = 20, d = -2 into the formula and you get $a_{25}$

anonymous · Answer

So a25 = 20 + (25 - 1)-2

kirbykirby · Answer

um "yes" although the -2 should be written in parentheses... (25 - 1)(-2) since you are multiplying it