please help!!! if i have this sequence 3,6,9,12..increasing by 3..what would be the arithmetic sequence, explicit sequence and recursive formula..HELP!

Question

anonymous · Answer

i think the explicit formula would be an=a1+(n-1)(d) 
an=3+(n-1)(3)
an=20+3n-3
an=3n+17

...but i'm not sure

anonymous · Answer

@hartnn do you know how to do this? emergency!!

hartnn · Answer

an=3+(n-1)(3)
then what u did ?

anonymous · Answer

lol i'm not sure, i did that a few days ago..uh, i have no idea where i got the 20 from:S

hartnn · Answer

an=3+(n-1)(3)
    = 3+ 3n -3 
    =.... ?

anonymous · Answer

en?

anonymous · Answer

3n

hartnn · Answer

es! thats your explicit formula :)

anonymous · Answer

yay, so how would i do recursive formula?

anonymous · Answer

i think the formula is an=an-1+d but i'm not sure

hartnn · Answer

hmm...recursive is even simpler. 
'each term increasing by 3' 
means if you add 3 to current, you get next term, did u get this ?

anonymous · Answer

yess

hartnn · Answer

an=an-1+d  is correct formula, where you just need value of d

hartnn · Answer

$\large a_n=a_{n-1}+d$

hartnn · Answer

d=... ?

anonymous · Answer

3

hartnn · Answer

yes! so recursive formula is just 
$a_n=a_{n-1}+3$
thats it!

anonymous · Answer

seriously? woahh :) thanks! and the last one is arithmetic sequence?

hartnn · Answer

last one ?

anonymous · Answer

yess, i just needed to know how to do them three :)

hartnn · Answer

Question :
what would be the arithmetic sequence, explicit sequence and recursive formula
Answer : 
arithmetic sequence:  3,6,9,12.. (given)
explicit formula : an = 3n
recursive formula : an = a(n-1)+3
what else is remaining ?

anonymous · Answer

uh, the a?

precal · Answer

|dw:1360881808862:dw|this is also recursive