Question

@kainui http://prntscr.com/az05l5

Answer 1

@rebeccaxhawaii

Answer 2

http://prntscr.com/ayzxz5

Answer 3

wait i think i got it

Answer 4

its either A or B. right?

Answer 5

ITS A RIGHT?

Answer 6

I don't think so! So on her first run down the hill, that means i=1, the thing in there has to be 5,

so A and B both have the same thing: 2*1+3 = 5 OK works, but watch out, it also works for the others C and D since 3*1+2=5!

She goes 3 more jumps every time around so if she went 5 when i=1 then 5+3=8 should be what it is on the next run down the hill!

So for i=2 you have to have 2*i+3=8 if it's A or B and the other case if it's C or D it must be 3*i+2=8. So which one is it?

Answer 7

wait wouldnt a_1 be 2 or 3.

Answer 8

I can't tell, explain yourself. I'm not familiar with the notation you use so I don't know what \(a_1\) is representing. :X

Answer 9

http://prntscr.com/az00uv

Answer 10

look how a_1 in this problem is 4

Answer 11

Yeah, ok good, so for A and B what is \(a_i\)? What is \(a_i\) for C and d?

Answer 12

a and b are 2
c and d are 3

Answer 13

Aha, close but \(a_i\) is the entire term in there:

so A and B has: \(a_i = 2i+3\)

and C and D has \(a_i = 3i+2\)

Answer 14

Go back to problem 4 and you will see they did it the same way there too

Answer 15

what does the 2 and 3 represent (number before i)

Answer 16

it means multiply i*2, I left out the multiplication sign. Here I'll write some of them out maybe that will help, so looking specifically at A and B:

\[a_i = 2*i+3\]\[a_1=2*1+3=5\]\[a_2=2*2+3=7\]\[a_3=2*3+3=9\]\[a_4=2*4+3=11\]

Answer 17

no i know that, but like what does it represent?

Answer 18

in context

Answer 19

Ahhh ok it represents the number of times you add on every time she goes around again. Specifically this sentence right here:

"on each trip down the slope, she will do 3 more jumps than before."

each trip is counted by i. i=1 is the first trip, i=2 is the second trip, etc... and doing 3 more jumps each time means on the first trip she did 3 jumps and then on the next trip she has to do 3 more so 3+3=2*3.

Kinda hard to wrap your brain around!

Answer 20

oh okay so 3 more each time. why the +2?

Answer 21

Good question. Well first let's just think about what we expect to happen without going through with this fancy notation.

"On her first trip she did 5 jumps"

Ok so we know she will do 3 more jumps on her second trip right? So we end up with

8 jumps on her 2nd trip.

since 5+3=8.

But because 5=3+2 already, we have 3+2+3 = 3*2+2. So the "2" from the original starting "5" is what persists through the total number of jumps since she is adding on 3 each time.

Answer 22

kai its C right?

Answer 23

I honestly don't know cause I didn't calculate it but the form for C and D are the correct ones. gimme a sec

Answer 24

1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26... kai

Answer 25

I got C lol

Answer 26

http://www.wolframalpha.com/input/?t=crmtb01&i=sum_i%3D3%5E10+(3i%2B2)

Answer 27

yeah kai no cheat -.- hawaii is disappointed

Answer 28

I seldom crave squash, but when I do I would like it in pie form

Answer 29

next thread

Answer 30

Haha the way to not cheat is not much more work lol you can do it by seeing this then:

\[\sum_{i=3}^{10} 3i+2 = 3\sum_{i=3}^{10}i + 2\sum_{i=3}^{10}1 \]
then you can evaluate those simpler individual sums

Answer 31

http://openstudy.com/study#/updates/5725eca7e4b00ff203b80447 come along children