# I need help with various homework questions from precalc chapter 2

• September 29th 2012, 12:54 PM
Tedward570
I need help with various homework questions from precalc chapter 2
For all of the following questions please give as much help as you can, preferiably tell me how you solved it as well as the correct answer. Thank You

1. A rectangle has one corner on the graph of y=9-x^2 , another at the origin, a third on the positive x axis, and the fourth on the postive y axis. Express the area of the rectangle as a function of x.

2. If the points of a f(x) graph are (-6,0) (-4,-3) (0,-3) (2,5) and (8,0) then what would the points be for the graph of |f(x)| and the graph f(-x)

A farmer has 480 feet of fencing available to enclose a rectangular field. One side of the field lies along a river, so only 3 sides require fencing.
a. express the area A of the rectangle as a function of x, where x is the length of the side perpindicular to the river ( i think it is f(a)= (480-x/2)x
b. for what value of x is the area largest?
c.what is the maximum area?

a. The domain of f(g(x)) where f(x)= 16/x-4 and g(x)= √x-2 (square root symbol extends over entire binomial)
b. the domain of f(g(x)) if f(x)= x/x+3 and g(x)=2/x (is it x≠0, x≠2/3?)

(f-h)(x) when h(x)=-2x+5 and f(x)=3x+1 (is it 5x-4?)

THat is it. THank You for looking!
• September 29th 2012, 12:57 PM
johnsomeone
Re: I need help with various homework questions from precalc chapter 2
Where are you stuck?
• September 29th 2012, 01:19 PM
Tedward570
Re: I need help with various homework questions from precalc chapter 2
for the first one i really have no idea what to do, im pretty sure i am supposed to setup a diagram and plug numbers into the distance formula
• September 29th 2012, 03:59 PM
johnsomeone
Re: I need help with various homework questions from precalc chapter 2
Quote:

Originally Posted by Tedward570
for the first one i really have no idea what to do, im pretty sure i am supposed to setup a diagram and plug numbers into the distance formula

Actually, it's not even that complicated. If you read #1 carefully, and draw a diagram representing it, then what the rectangle is should hopefully be clear. Since all you'll want is the rectangle's area, all you'll need to know are its base and height.

Note that y = 9-x^2, in the first quadrant, is an downward pointing parabola with vertex at (0, 9) and going through (3, 0). So try to draw the diagram. Remember also that the graph of a function y=f(x) is the points where, if x = a, then the y value is the height above (below for y<0) the x axis - and hence (a, f(a)) is on the graph.
• September 29th 2012, 05:09 PM
Soroban
Re: I need help with various homework questions from precalc chapter 2
Hello, Tedward570!

#2 is a strange one . . .

Quote:

$\text{2. If the points of a graph of }f(x)\text{ are: }(\text{-}6,0),\:(\text{-}4,\text{-}3),\: (0,\text{-}3),\:(2,5)\text{ and }(8,0),$

$\text{(a) what would the points be for the graph of }|f(x)|\,?$

$|f(x)|$ means all the y-values becomes positive.

The points are: . $(\text{-}6,0),\:(\text{-}4,3),\:(0,3),\:(2,5),\:(8,0)$

Quote:

$\text{(b) what would the points be for the graph of }f(\text{-}x)\,?$
Without knowing the nature of $f(x)$, we cannot answer the question.

We do not know the values of: $f(6),\:f(4),\:f(\text{-}2),\: f(\text{-}8)$
• September 30th 2012, 10:58 AM
Tedward570
Re: I need help with various homework questions from precalc chapter 2
Thank you for ypour help on these questions. If someone could help on 3a it would be appreciated
• September 30th 2012, 05:24 PM
Tedward570
Re: I need help with various homework questions from precalc chapter 2
hey could somebody give me the answer to number 1
• September 30th 2012, 06:00 PM
skeeter
Re: I need help with various homework questions from precalc chapter 2
Quote:

Originally Posted by Tedward570
hey could somebody give me the answer to number 1

see post #4
• September 30th 2012, 06:28 PM
Prove It
Re: I need help with various homework questions from precalc chapter 2
Quote:

Originally Posted by Tedward570
hey could somebody give me the answer to number 1

You're not going to get any answers or solutions. You have been given some instructions to follow in previous posts, now it is up to YOU to do your own homework.
• September 30th 2012, 06:59 PM
Tedward570
Re: I need help with various homework questions from precalc chapter 2
Other math forums helped me more. Im done with this site.
• September 30th 2012, 07:02 PM
skeeter
Re: I need help with various homework questions from precalc chapter 2
Quote:

Originally Posted by Tedward570
Other math forums helped me more. Im done with this site.