# need help with my math hw lol

Discussion in 'Community Discussion' started by GD0X, Feb 1, 2012.

1. ### GD0X Guest

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Mar 20, 2011
#1
1. f(x)=4/(4x-3) what does f^-y equal?

2. h(x)=3-(x+5/x-7) what is h(9)^-1?

3. f(x)=x-1/x^2+1
g(x)=x+10/x+13

What is (f o g)(x)?
and what is
What is (g o f)(x)?

4. h(x)=square root of (1/x^2+7) + 16

if f(x)=square root of x, then find a function g such that h=f o g

if f(x)=square root of x+16, then find a function g such that h=f o g.

Don't have any resources available at the moment, but need some help haha.

2. ### ender land macrumors 6502a

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Oct 26, 2010
#2
This might help:

http://math.aa.psu.edu/~mark/Math22/combine.pdf

3. ### Fazzy macrumors 6502

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#3
You need help or you want someone to do it for you?

4. ### mantic macrumors 6502a

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#4

Yeah and that looks like pre-cal-- been a while..

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6. ### ender land macrumors 6502a

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#6

I have no idea wtf type of notation "f^-y" is though... and I've had a lot of math in college

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Feb 19, 2011
#7
Find the inverse of h(x), then plug in 9.

That's a composite function, just incase you need to dig up more info (Ender Land's link looks good though).

8. ### Surely Guest

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9. ### ender land macrumors 6502a

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#9
That's what I though initially but the first example makes no sense. Unless it was supposed to be

1. f(x)=4/(4x-3) what does f(y)^-1 equal?

Joined:
Feb 19, 2011
#10
I honestly have no idea about 1, but it makes sense for 2, surely? (I know, I just set up a joke there).

11. ### ender land macrumors 6502a

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Oct 26, 2010
#11
I'm not sure.

Maybe it literally means.... f(x)^-y

12. ### visim91 macrumors 6502

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#12
A vendor seeking extra help for nonsensical Pre-Calc functions?
I have a strange and creeping doubt that this may be, in fact, an advertisement for the Sylvan Learning® Center.

13. ### wordoflife macrumors 604

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Jul 6, 2009
#13
#1 Not sure what it's asking. I'd just solve for x instead of y. So set the equation to "x="
#2 Not sure what it's asking again, but I'd plug 9 in and then find the inverse of the equation, basically like #1.
#3 You basically plug the equations into the each other.
(f o g)(x)= g(f(x)) (plug equation F into G)
(g o f)(x) = f(g(x)) (plug equation G into F)

Isn't precalulus all about trigonometry? This is Algebra, no?
I know my trigonmetry very well. QUICK : 3π/4

14. ### GD0X thread starter Guest

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Mar 20, 2011
#14
no no. I just have website haha

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i know mostly how do it, but i still need helping actually getting to the answer.

15. ### mantic macrumors 6502a

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#15
Yeah, it has to be Pre-Cal Trig..

16. ### fireshot91 macrumors 601

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#16

Easy enough.

I don't feel like continuing...it's the same stuff.

17. ### yg17 macrumors G5

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18. ### borisiii macrumors 6502

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#18
WolframAlpha is your friend. It will even show you the stages to solve each problem...

19. ### Hastings101 macrumors 68020

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#19
I got C's in math all four years of high school. Are you sure you want my help?

20. ### chrono1081 macrumors 604

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#20
I'd love if there was a math book that explained real world uses for all that stuff. I'd buy it in a heart beat! (Seriously I would).

A lot of math I thought would be useless pops up in video game programming (I can't tell you how often sine and cosine waves came in handy, or trig, or even some discrete math) but even when I go back and study math to brush up on my skills I get lost because nothing ever explains a real world purpose for certain types of math.

Sorry didn't mean to hijack

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22. ### CalBoy macrumors 604

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May 21, 2007
#22
Basic functions like these are useful in lots of fields, or rather one must understand the fundamentals before grasping the more sophisticated elements that a particular profession will use.

That said, OP you need to learn how to do this, not try to get easy answers. Filling in an easy answer will get you a rubber stamp today but an obstacle tomorrow. Ask us what you don't understand, don't expect us to think for you.

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25. ### iJohnHenry macrumors P6

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#25
Not my high-school. We could afford real numbers.