Question

The first term of an arithmetic progression is -3 and the common difference is 8.
What is the 28th term?

Answer 1

We're told that `The first term of an arithmetic progression is -3` so this means \(\Large a_1 = -3\)


Also, we're given ` the common difference is 8` which tells us that \(\Large d = 8\)


Do you agree with everything so far?

Answer 2

Yes

Answer 3

what we do next is plug those values into the formula below and simplify

\[\Large a_n = a_1 + d(n-1)\]
\[\Large a_n = -3 + 8(n-1)\]
\[\Large a_n = -3 + 8n-8\]
\[\Large a_n = 8n-11\]

this is our nth term formula

Answer 4

It asks: `What is the 28th term?`
so they want us to plug in \(\Large n = 28\) into the nth term formula


\[\Large a_n = 8n-11\]
\[\Large a_{28} = 8(28)-11\]
\[\Large a_{28} = ???\]
I'll let you finish up

Answer 5

So it'd be 213? Thanks!

Answer 6

`So it'd be 213? `
yes, correct