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CPhill
Nombre de usuario
CPhill
Puntuación
128578
Membership
Stats
Preguntas
56
Respuestas
42583
56 Questions
43000 Answers
+10
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+128578
Blocked Posts
I just wrote to the site manager to let him know that this is happening....I'll try to "unblock" as many posts as possible ( but realize that I can't stay on here all day )
CPhi
lee mas ..
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CPhill
7 ago 2023
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HAPPY BIRTHDAY , MELODY !!!
I baked you a cake.....be sure to share !!!!!
lee mas ..
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CPhill
16 abr 2022
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HAPPY BIRTHDAY, MELODY !!!!
lee mas ..
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CPhill
16 abr 2021
+54
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+128578
Gotta take a break folks !!!!
I'll come back a little later and try to answer as many questions as I can [ or as many as I know how to do !!! ]
lee mas ..
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CPhill
26 mar 2020
+43
1
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HAPPY BIRTHDAY, HECTICTAR !!!
She is one of the best "answerers" on this site [ even though she IS from Alabama....well.....everyone can't be perfect !!!! (Hehehe!!) ]
lee mas ..
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CPhill
14 oct 2019
+53
2
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+128578
'Waiting For Moderation'
I see that this has been happening quite a bit.....
If you "right click" on the image and select "Copy Image Address".....you can open up a new browser window and paste this address into it.....hit "Enter"
lee mas ..
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CPhill
21 oct 2018
+83
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4th Anniversary For Me !!!
Been on this site for 4 years now.....my thanks to Melody (and Andrew) for recommending me as a "mod".....I've learned quite a bit and "met" a lot of good people on here.....I've even managed (somehow) to help some of them....!!!
lee mas ..
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CPhill
13 mar 2018
+25
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Hey, guys.....I'm going to be gone for awhile....If you can hang on....I'll answer as many questions as I know how in just a bit....
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CPhill
6 mar 2018
+31
1
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7
+128578
I'm Out Until This Afternoon...You Kids Have Fun !!!
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CPhill
13 feb 2018
+48
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+128578
HAPPY BIRTHDAY, HECTICTAR !!!!
You are a real asset to the forum.....!!!!!
Here's your cake.....enjoy.....!!!!
lee mas ..
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CPhill
14 oct 2017
+31
3
3966
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+128578
Going To The Picnic
This one isn't too difficult....give it a try.....!!!!!
lee mas ..
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CPhill
25 sept 2017
+27
2
6907
7
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How Much Do They Weigh ????
This is another problem from American puzzle-maker Sam Lloyd.....
Five little girls taken in couples weigh 129 pounds, 125 pounds, 124 pounds, 123 pounds, 122 pounds, 121 pounds, 120 pound, 118 pounds, 116
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CPhill
23 sept 2017
+25
2
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+128578
The Width Of The River.....
Here is a problem I've always liked...it was devised by one of the great American "puzzleists" of all time, Sam Lloyd
It has been posted on the forum before, but not in a while.....maybe we have some new people who would like
lee mas ..
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CPhill
20 sept 2017
+30
2
3222
10
+128578
ReCaptcha Verification
I don't know if others are having this problem or not......when using Opera or Firefox I had to do the ReCaptcha thing when submitting answers.......however.......using Google Chrome seems to solve this problem - for me anyway....
Comments???
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CPhill
19 mar 2017
+35
1
3767
6
+128578
Happy Pi Day..(3.14)....Everybody.....!!!!!
lee mas ..
hectictar
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CPhill
14 mar 2017
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#2
+128578
+3
The diameter is 2
To see this, note that the circumference is given by C = 2πR, or C=2Rπ. But 2R = D, where D is the diameter.
Therefore, C=Dπ
So 6.28 = Dπ
And if we let π = 3.14
Then, 6.28 = D * 3.14
So D = 6.28 / 3.14 = 2
CPhill
26 mar 2014
#1
+128578
+2
Example:
Twice a number = 2n
So, 5 less than twice would be
2n - 5
CPhill
25 mar 2014
#3
+128578
+2
Take a look at this website, Stu. I've found that his explanations are pretty good. He also gives some examples.
http://tutorial.math.lamar.edu/Classes/CalcI/DerivativeIntro.aspx
If you have any specific questions, post them to the forum.
Hope this helps.
CPhill
25 mar 2014
#2
+128578
+2
Although I'm not the most "technical" user of the calculator, it will add and subtract fractions (and reduce them to simplest form). It will also convert an "unknown" decimal to a fraction.
Examples
108/357
9/93+8/102
0.1752055660974067
I'm not sure what you might be after, but if you have more specific questions, post them to the forum and we'll see if we can answer them.
CPhill
25 mar 2014
#1
+128578
+2
First, let sin(x) = x
So
3SIN(x)^2-7SIN(x)-3=0
= 3x^2 - 7x - 3 = 0
Solving, we have.....
3x^2 - 7x - 3 = 0
This implies that sin(x) = (7 - √85) / 6 and sin(x) = (7 + √85) / 6
The second answer is impossible, since it implies that sin(x) > 1
Solving for the first, we have
asin(((7-sqrt(85))/6))
Hope this helps
CPhill
25 mar 2014
#6
+128578
+2
Bertie
Your method of substituting cos(pi/3) for 1/2 and sin (pi/3) for (√3)/2 is quite ingenious!!!!
I like that
MUCH BETTER
!!!
CPhill
25 mar 2014
#3
+128578
+2
sqrt(3)cos(x) - sin(x)= 1
Let's see if this works
(add sin(x) to both sides and square both sides)
3(cos(x)^2 = 1 + 2sin(x) +sin(x)^2
(using cos(x)^2 = 1 - sin(x)^2, we have)
3*(1 - sin(x)^2) = 1 + 2sin(x) +sin(x)^2
(Simplify)
4*sin(x)^2 + 2*sin(x) - 2 = 0
(Divide through by 2)
2*sin(x)^2 = sin(x) -1 = 0
(Factor)
(2sin(x) -1) (sin(x) +1 ) = 0
Solving, we get x = (pi/6 + 2*pi*n , 3*pi/2 +2*pi*n)
Another 2nd quad angle, 5*pi/6, solves (2sin(x) -1 = 0), but it doesn't "work in the original problem) (due to "squaring," we get an extraneous solution??)
I think that may be it.....but check my work and method!!
CPhill
25 mar 2014
#1
+128578
+2
This is an interesting one........
For all real numbers x,
√(x)^2 = IxI = x if {x ≥ 0 and -x if x < 0}
So, √(-1)^2 = I-1I = -(-1) = 1
Now, many people assume that the result could be "-1" - due to following faulty "proof."
Step 1 √(-1)^2 =
Step 2 √(-1) * √(-1) =
Step 3 ( i * i ) =
Step 4 ( -1 )
The problem comes in the transition from Step 1 to Step 2.
In general, √(a * a) = √(a) * √(a) only if a ≥ 0. (Thus, we can't "split" the radicals in this manner.)
I think that's it !!!
CPhill
22 mar 2014
#1
+128578
+2
How do you Solve this?
2(x+3) - 2x^2(x+3) = 0
In my answer sheet they rewrite it to (x+3) * (2-2x^2) = 0
Im unsure what happens to the other (x+3)
They (almost) took the greatest common factor, (x + 3), out of both terms......... !!!!
We can also take a "2" out !!!
Doing this, we get
2 * (x + 3) * (1 - x^2) = 0
We can get rid of the 2 by dividing through, so this becomes
(x + 3) * (1 - x^2) = 0
To solve, set each factor = 0
The first one is easy
x + 3 = 0
Subtracting 3 from both sides, we get
x = -3 and that's one solution
Now, setting the other factor to 0 we get
1 - x^2 = 0
This can be factored as
(1 - x) * (1 + x) = 0
And setting these two things to 0 (as before), we get the other two solutions of 1 and -1
Hope this helps
CPhill
22 mar 2014
#1
+128578
+2
how do i do a problem like this 1/2(w-4)??
I assume you just want to "distribute" the 1/2 over the terms in the parentheses.
This would just give us
1/2w - 2
CPhill
21 mar 2014
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