• Today, 02:28
'Factor: (x^2-9)(x^2-16)\le0 Continue factoring...:D
1 replies | 10 view(s)
• Today, 02:25
You want to determine the roots of both the numerator and denominator as your critical numbers (i.e., values for which the expression can change...
1 replies | 11 view(s)
• Today, 02:02
Move everything to the LHS, and then combine all terms into a rational expression...what do you then have?
1 replies | 15 view(s)
• Yesterday, 22:03
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
We require both: 0<x 0<12-x Combined, this gives us: 0<x<12
18 replies | 132 view(s)
• Yesterday, 21:41
For better forum organization, I have merged the 4 threads pertaining to Stanley A. Ellisen quotes into one thread. This way they can all be...
4 replies | 42 view(s)
• Yesterday, 21:12
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
x and x - 12 represent lengths (assumed to be in cm)...and so must be positive. Lengths cannot be negative, and if we are to actually have two pieces...
18 replies | 132 view(s)
• Yesterday, 19:13
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
At this point you can multiply through by 8 to get: x^2-12x+32>0 Then factor: (x-4)(x-8)>0 Now solve this inequality, subject to:
18 replies | 132 view(s)
• Yesterday, 11:04
When I was a student, I found one of the best ways to understand things is to look at them in general terms. For example, in this problem, rather...
21 replies | 179 view(s)
• Yesterday, 10:49
What we see is that we must have: L=W And so, what we have found is that for a rectangle of a given area, the perimeter is the smallest it can...
21 replies | 179 view(s)
• Yesterday, 10:34
Your next step should be: (L-W)^2=0 So, how must L and W be related in order for this to be true?
21 replies | 179 view(s)
• Yesterday, 10:28
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
No, what we want is: A\left(W_1\right)+A\left(W_2\right)>5 A(x)+A(12-x)>5 Now, the arguments for the area function represent wire lengths,...
18 replies | 132 view(s)
• Yesterday, 10:10
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
Yes, now we need to answer the question: For which values of x will the combined areas of the squares exceed 5 cm^2? We have two pieces of wire...
18 replies | 132 view(s)
• Yesterday, 10:00
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
Okay, you have a piece of wire whose length is let's say W...you bend it into a square...what is the perimeter of the square? Then using your formula...
18 replies | 132 view(s)
• Yesterday, 09:55
Yes, once you simplify, you will find the implication. :D
21 replies | 179 view(s)
• Yesterday, 09:53
Yes, now combine terms on the LHS...:D
5 replies | 48 view(s)
• Yesterday, 09:44
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
Let's use x for the length of the sides of the square, so we have: P=4x A=x^2 Now, we want to replace x in the formula for the area with an...
18 replies | 132 view(s)
• Yesterday, 09:39
You're just seeing what the equation implies about the relationship between L and W. :D
21 replies | 179 view(s)
• June 23rd, 2017, 22:50
We have: \sqrt{LW}\le\frac{L+W}{2} When I ask "when does equality occur," I am essentially asking you to solve: \sqrt{LW}=\frac{L+W}{2} ...
21 replies | 179 view(s)
• June 23rd, 2017, 21:56
I would look at a substitution like: u=\sqrt{x^2+4x+3}\implies dx=\frac{u}{x+2}\,du And the integral then becomes: I=\int\frac{1}{u^2+1}\,du
1 replies | 27 view(s)
• June 23rd, 2017, 19:33
MarkFL replied to a thread Two Pieces of Wire in Pre-Calculus
What is the area $A$ of a square whose perimeter is $P$?
18 replies | 132 view(s)
• June 23rd, 2017, 19:25
You don't want to multiply an inequality by an expression whose sign is unknown...arrange everything to one side and then get your critical values...
5 replies | 48 view(s)
• June 23rd, 2017, 19:21
You are assuming x is positive when you do that. A better step is to subtract x/2 from both sides: \frac{2}{x}-\frac{x}{2}<0 Combine terms: ...
2 replies | 37 view(s)
• June 23rd, 2017, 15:00
MarkFL replied to a thread Quadratic Inequality in Pre-Calculus
Yes, we have a parabola opening upwards, and given that it has two real roots, we should expect to find it to be negative in between its roots. :D
7 replies | 73 view(s)
• June 23rd, 2017, 14:44
Okay, I have several issues here: 1.) We ask that you post no more than 2 questions per thread: 2.) You've shown no effort:
1 replies | 66 view(s)
• June 23rd, 2017, 13:38
In this problem, you have a function representing a parabola that opens upwards. We should then expect, given that it has two real roots, that the...
7 replies | 77 view(s)
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28 Visitor Messages

1. Hello and welcome back to MHB, Fernando Revilla!

We are happy to see that you have returned, and we look forward to your continued participation here!

On Behalf Of MHB's Staff,

Jameson.
2. Hello and welcome back to MHB, Fernando Revilla!

We are happy to see that you have returned, and we look forward to your continued participation here!

On Behalf Of MHB's Staff,

Jameson.
3. Welcome back, Fernando! Glad to see you've rejoined the party!
4. Woow , it's been a while. Welcome back
5. Welcome back, Fernando!
6. Hey! There you are! I was wondering if you'd be back. We missed you!
7. Hey Fernando, nice to see you back!
8. Congratulations on the 500 post mark! It's great that you've been so active this year Looking forward to the next 500 posts.
9. hola profesor fernando que pena escribir en español pero no se ingles, queria saber si usted conoce alguna aplicacion de las integrales sin(x*x*x*x), he desarrollado un metodo numerico para calcularlas en cualquier valor comprendido en el intervalo de (4,infinito) y mi abogado me dice que tengo que encontrar una aplicacion para poder proteger y blindar de una forma mas segura los derechos de autor, estare pendiente de su respuesta, o si conoce a alguien que me pueda ayudar le agradeceria enormemente, gracias.

hello fernando teacher wanted to know if you know any application of the integral sin (x * x * x * x), I have developed a numerical method to calculate any value in the interval (4, infinity) and my lawyer tells me I have to find an application in order to protect and shield in a more secure copyright, I will be aware of your answer, or if you know someone who can help me I would appreciate greatly, thanks.

att
jefferson alexander vitola
10. LOL! Nicely put!
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Head of Mathematics Department, I.E.S. Sta Teresa, Madrid.
Prof. of Mathematical Methods, Univ. Alfonso X El Sabio, Madrid.
(Up until the 2008/2009 academic year. I am now devoted to investigation).
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