Math Help Forum

Area of a Rectangle

Murphie — Fri, 03 Jul 2009 23:46:14 GMT

Having trouble with this seemingly simple problem, help is much appreciated!

Three sides of a fence and an existing wall form a rectangular enclosure. The total length of fencing used for the three sides is 240 ft. Let x be the length of each of the two sides perpendicular to the wall.
a. Draw a picture and write a formula for the area of the enclosure.
b. Then find the value for x that would give an area of 5500 ft^2

a. Pictures easy but would the formula for the area of the rectangle be x times y = 5,500?

b. Don't really know how to find the exact value for x, so I just used trial and error to find x to be around 214.35 and y to be around 25.65.

Help with finding the exact value and the formula would be great.

taylor polynomial

eniuqvw — Fri, 03 Jul 2009 23:35:56 GMT

I need to find the third-degree taylor polynomial at a for f(x) = sin9x and a = pi/54. I guess it's not clear to me what to do with the 9 in sin9x, does it end up in the final answer or only to calculate the coefficients? If someone could explain this polynomial intuitively (particularly what to do with the 9), that would be awesome.

Some Trig Help: Find the exact value of cos(−5pi/12)

mvho — Fri, 03 Jul 2009 23:31:48 GMT

I've used the sum and difference identity for cos and here is my answer:

Cos -5pi/12 I translate as -75 degrees, so I used my known angles which were:

pi/-6 and -pi/4.

I also know that -5pi/12 is in the 4th region so the value should be positive (All Students Take Calculus).

From the Cosine Sum formula we have:

Cos(a+b)=Cos(a)Cos(b)-Sin(a)Sin(b)
Cos(-pi/4 + -pi/6)= Cos(-pi/4)Cos(-pi/6)-Sin(-pi/4)Sin(-pi/6)
Cos(-pi/4 + -pi/6)=(sqrt2/2)(sqrt3/2)-(sqrt2/2)(1/2)

.....

So what Did I do wrong guys?

Angle problem: Changing algebric expressions to angles

Julian.Ignacio — Fri, 03 Jul 2009 23:15:26 GMT

We prefer that the answers are defined in RR to the second power (I don't know what RR to the second power means). Answer graphically each answer in the same cartesian coordinate system.
f(x)=2x
h(x)=2x+2
g(x)2x-1
i(x)=2x-4

differential question

superdude — Fri, 03 Jul 2009 22:53:06 GMT

for what values of k does the function y=costkt satisfy the differential equation 4y''=-25y?

show this series diverge

wellfed — Fri, 03 Jul 2009 22:42:05 GMT

Hi I am stuck on the following problem, your help is greatly appreciated.

given 0" title="a_n > 0" style="border: 0px; vertical-align: middle;" /> and with show the series diverges.

Numerical analysis: What are N, N*, Z and Q????

Julian.Ignacio — Fri, 03 Jul 2009 22:36:05 GMT

I can't seem to understand what they are..this is what the teacher explained us

N=Set of natural numbers
N*=??? I dunno....
Z=set of intergers...
Q= Set of rational number (Most complex one for the matter...)

Parametric Equations of a Line

adkinsjr — Fri, 03 Jul 2009 21:29:30 GMT

I am to find the parametric and vector equations for the line passing through the given points.

P(0, 1/2, 1) Q(2, 1, -3)
The line through the points is parrellel to:
V = rq - rp (q and p are subscripts correponding to points P and Q)
V = < 2-0, 1-1/2, -3-1>
= <2, 1/2, -4>
R= r + Vt
= < 0 , 1/2, 1 > + < 2t , t/2 , -4t >
= < 2t , 1/2 + t/2 , 1-4t >
Parametric equations
x = 2t
y = 1/2 + t/2
z = 1 - 4t
The answer in the book is:

x = 2 + 2t
y = 1 + t/2
z = -3 - 4t

I have done many questions like these and I basically do the same procedure, and I get the correct equations. I don't understand how this particular set of points is different.

field question help please

canuhelp — Fri, 03 Jul 2009 20:58:57 GMT

R(x)={P(x)/Q(x): p and q are polynomials} can you explain me how can i show this is a field?i reguest explain me step bye step please.thanks for your helps.

Motion

Joker37 — Fri, 03 Jul 2009 20:40:54 GMT

A car travelling with a constant speed of 80 km/h passes a stationary motorcyle policeman. The policeman sets off in pursuit, accelerating to 80 km/h in 10.0 s and reaching a constant speed of 100km/h after a further 5.0 s. At what time will the policeman catch up with the car?

Method of cylindrical shells

klooless — Fri, 03 Jul 2009 19:25:13 GMT

Could anyone help me set up this integral?

Question:
Use the cylindrical shell method to find the volume of the solid using the region bound by these curves about the x-axis;

y=√x , y=0 , x+y=2

Thank you!!

Chi square

klore717 — Fri, 03 Jul 2009 18:46:48 GMT

at a=.01, is the frequency of disciplinary action independant of the abusers level of privilege.

level disciplined not disciplined total

low 20 11 31

medium 42 3 45

high 33 3 36

column total 95 17 112

please help me

flower3 — Fri, 03 Jul 2009 18:44:08 GMT

(1) =

(2) z is either real or pure imaginary

Anova

klore717 — Fri, 03 Jul 2009 18:43:01 GMT

test the hypothesis at the .05 significance level that the treatment means are equal.

treatment 1: 9,7, 11, 9, 12, 11
treatment 2: 13, 20, 14, 13
treatment 3: 10, 9, 15, 14, 15

a. state null & alternate hypothesis
b. decision rule
c. SST, SSE, and SS total
d. ANOVA table
e. state your decision

having a problem with a few questions:

heidigaz — Fri, 03 Jul 2009 17:58:43 GMT

Hi there - I'm new here (as of 2 hours ago), and am praying that this site will help me in my worst favorite subject - the "A" word!!! (algebra (Headbang))

Here are a few that I'm just not being able to grasp at and I've tried for over 45 minutes to firgure these two out! (actually, there are more than two, but I figure if I can get these two explained, it may help with the others.

Any one's help will be so forever grateful!!!!
Thank you!

Solve the system of equations by substitution:

2x - 18 = -y
4x - y = 0

I'm not an idiot by any means, but algebra is not my "cup of tea".

Thanks!!!