Question

whats the equation to find the indicated value?
a1=-3 and d=5, determine a15

Answer 1

If you're dealing with an arithmetic sequence (which it looks like you are), then you use

\[\Large a_{n} = a_{1} + d(n-1)\]

Answer 2

a1 = -3 and d = 5

\[\Large a_{n} = a_{1} + d(n-1)\]

\[\Large a_{n} = -3 + 5(n-1)\]

then plug in n = 15

\[\Large a_{15} = -3 + 5(15-1)\]

\[\Large a_{15} = 67\]

Answer 3

would \[an=a1+(n-1)d \] be the same equation cuz thats one of the equations my teacher gave me but i wasnt sure?

Answer 4

yes it is

(n-1)d is saying "(n-1) times d"

and d(n-1) is the same thing just in a different order

Answer 5

this is true because you can multiply two numbers in any order

ex: 3*2 = 2*3 = 6

Answer 6

alright thank you!

Answer 7

np