Question

Find an equation for the nth term of the arithmetic sequence.

-3, -5, -7, -9, ...

Answer 1

arithemtic sequences are well known for their common difference

Answer 2

so first step: find common difference

Answer 3

@freckles are you help her or should i help her?

Answer 4

it doesn't matter

Answer 5

go for it

Answer 6

okay you carry on

Answer 7

i am busy some other areas

Answer 8

ok
-3, -5, -7, -9, ...
common difference can be found be taking a term and subtracting its previous term

Answer 9

-2

Answer 10

what is -5-(-3)?

Answer 11

yes that is right

Answer 12

\[a_n=a+d(n-1) \\ \text{ so } d=-2 \\ a_n=a-2(n-1)\]
a is suppose to represent the first term

Answer 13

what is your first term

Answer 14

-3

Answer 15

so replacing a with -3
don't replace a_n with anything
a_n thing we are finding
\[a_n=-3-2(n-1)\]

Answer 16

thank you!

Answer 17

and as you can see we get all the terms when pluggin n=1,2,3,...
\[a_1=-3-2(1-1) \\ a_1=-3-2(0) \\ a_1=-3 \\ a_2=-3-2(2-1) \\ a_2=-3-2(1) \\ a_2=-3-2 \\ a_2=-5 \]
and so on ,,,

Answer 18

we will find find that a_n=-3-2(n-1)
that a_3=-7 and a_4=-9

Answer 19

and so on...
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