Given the sequence 9, 12, 15, which of the following is equivalent to...

Question

agentnao · Answer

$$\sum_{n=5}^{8} an$$

agentnao · Answer

I'm a bit confused as to what I'm trying to do here/what's being asked.

zarkon · Answer

it is equivalent to $$\sum_{n=3}^{5}3n$$

zarkon · Answer

;)

across · Answer

You know what they say, 50% of the battle is understanding the question. :P

agentnao · Answer

Haha, I fully agree across.

zarkon · Answer

and knowing is 1/2 the battle...GI Joe

agentnao · Answer

And Zarkon, that's definitely not the answer

agentnao · Answer

;)

anonymous · Answer

because knowledge is power

agentnao · Answer

Is anyone going to help me?

zarkon · Answer

how about $$a_n=3n$$ for $$n=3,4,5$$

;)

zarkon · Answer

don't really know what you are asking for

agentnao · Answer

The answer choices are 
 54

 102

 144

 162
If that helps. I'm not quite sure what i'm asking either, so I thought I'd put it on here.

zarkon · Answer

ah...

anonymous · Answer

Can scan the whole question as is and attach it ?

zarkon · Answer

102

agentnao · Answer

Zarkon, could you tell/show me how you got that?

agentnao · Answer

Given the sequence 9, 12, 15, which of the following is equivalent to $$\sum_{n=5}^{8} an$$  ?

 54

 102

 144

 162

zarkon · Answer

the sequence is ...

9,12,15,18,21,24,27,30,...

add the 5th,6th,7th,8th terms

agentnao · Answer

Oh my gosh. WOOOOW. I feel so dumb. Thanks Zarkon.