The first term of an arithmetic sequence is -5, and the tenth term is 13. Find the common difference.

8/9
1.8
2

Question

The first term of an arithmetic sequence is -5, and the tenth term is 13. Find the common difference.

8/9
1.8
2

bloomlocke367 · Answer

well, first things first, do you know how to find the common difference?

anonymous · Answer

nope..

bloomlocke367 · Answer

okay, well do you know what the common difference is?

anonymous · Answer

isnt it he difference between two sets of numbers?

bloomlocke367 · Answer

well yes, it's the difference between each pair of numbers in an arithmetic sequence

anonymous · Answer

yeah thats what i meant..

bloomlocke367 · Answer

i know c: so if I'm not mistaken, you can use this formula to solve for d $a_n=a_1+(n-1)d$

anonymous · Answer

i tried but it didn't get me the right number.. it gave me 1.5... so thats why i asked this..

bloomlocke367 · Answer

hm, what did you plug in?

anonymous · Answer

13= -5+(13-1)d

anonymous · Answer

i sort of guessed..haha

bloomlocke367 · Answer

that's where you made the mistake... it should be 13=-5+(10-1)d

bloomlocke367 · Answer

do you know why it should be that?

bloomlocke367 · Answer

solve that and tell me what you get.. the answer's an option c:

anonymous · Answer

is it because 13 is the tenth number?:D

anonymous · Answer

is it 2?!!

bloomlocke367 · Answer

yep! good job!

anonymous · Answer

yay! thank you so much. that made me understand what i was doing more.

bloomlocke367 · Answer

you're welcome! I'm happy to help

anonymous · Answer

i need your help again...

bloomlocke367 · Answer

okay, sure thing, just open a new post and tag me