# Final Exam Studying Time!

Since I'm studying for my final exam, I'm going to make you guys suffer. Any help would be appreciated in this. Here's the first one...

Find the 40th term of the arithmetic knowing the general term a(n) = a(n-1) + 4 and first term a1 = 13.

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cAm
What class is this?

(we just started that stuff in BC calculus :tongue2: )

College Math 2.

Astronuc
Staff Emeritus
If I am reading this right, isn't a(40) = a(1) + 39 * 4 = 13 +156 = 169?

or more generally, a(n) = a(1) + (n-1)*4

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That looks like it might be right. My friend said it was 159, but I think you've got it right.

cAm
edit: nvm, being stupid. :yuck:

vsage
I agree with Astronuc. Good luck studying with those finals. You have them so early? My physics 2/Linear Alg. finals are on my birthday in about 25 days :(

Okay, so here's another one:

A vector v has initial point P = (5, 2) and terminal point Q = (-3, -2). Find its position vector and write v in the form ai + bj.

Astronuc
Staff Emeritus
So vector to P is 5i + 2j and the vector to Q is -3i-2j, so take the difference.

or what vector added to the vector to P would give you the one to Q.

So would the final answer be 2i + 0j, which would be technically just 2i?

Astronuc
Staff Emeritus
5i + xi = -3i
2j + yj = -2j

So is xi = -8 and xj = -4?

Astronuc
Staff Emeritus
Yes, in the form ai + bj, a=-8, b=-4 or v = -8i -4j.

Okay, here's another...

What are the coordinates for graphing the equation y = sin 6 Ø by plotting points?

Any help would be tremendously appreciated.

ek
Poweranimals said:
Since I'm studying for my final exam, I'm going to make you guys suffer. Any help would be appreciated in this. Here's the first one...

Find the 40th term of the arithmetic knowing the general term a(n) = a(n-1) + 4 and first term a1 = 13.
I wish I was taking your math class. That sounds like grade 11 math.

Sigh.

cAm
Poweranimals said:
Okay, here's another...

What are the coordinates for graphing the equation y = sin 6 Ø by plotting points?

wouldn't you just take the points for the graph y=sinx and increase the 'x' coordinates by a factor of 6?

cAm said:
wouldn't you just take the points for the graph y=sinx and increase the 'x' coordinates by a factor of 6?
Yeah, you're right. But I'm stiff baffled as to what coordinates are y=sinx.

vsage
cAm said:
wouldn't you just take the points for the graph y=sinx and increase the 'x' coordinates by a factor of 6?
If I understand the equation correctly, the equation would be shrunk horizontally by a factor of 6. Either the question wants a graph of $$sin(6\Theta)$$ or maybe the critical points where the graph crosses the x axis. Don't you just love semantics?

I hate math. :p