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MarkFL
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MarkFL
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Join Date
11-24-2012
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11:04 PM
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Older Activity
06-20-2018,
04:57 PM
MarkFL
replied to a thread
Jomo_Denis
in
Math Odds & Ends
For an additional $20, I'll write an ode to you. ;)
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11 replies | 246 view(s)
06-20-2018,
02:59 PM
MarkFL
replied to a thread
Jomo_Denis
in
Math Odds & Ends
What have y'all done to Denis? He's always been a good poster at MHB. :)
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11 replies | 246 view(s)
06-19-2018,
03:49 PM
MarkFL
replied to a thread
Vanished posts...
in
Administration Issues
If I were an admin, I would try the "Update Post Counts" option under: AdminCP -> Maintenance -> General Update Tools edit: I missed the part...
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4 replies | 144 view(s)
06-18-2018,
02:26 AM
MarkFL
replied to a thread
a tricky problem about arranging books
in
Pre-Algebra
You did well to begin with: \displaystyle {7 \choose 4}=35 Now, you need to observe that there are 4! ways to order the 4 books chosen...so the...
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3 replies | 135 view(s)
06-14-2018,
11:49 AM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
The best I can tell, you are essentially given to verify: \dfrac{A\sin(\theta)}{A+A\cos(\theta)}= \tan\left(\dfrac{\theta}{2}\right) I would...
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20 replies | 632 view(s)
06-12-2018,
09:17 PM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
Yes, the commutative property of addition tells us: a+b=b+a
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20 replies | 632 view(s)
06-12-2018,
02:44 PM
MarkFL
replied to a thread
Sum, Product of Roots alpha, beta of 4x^2 - x + 7 = 0
in
Intermediate/Advanced Algebra
I would proceed as Subhotosh Khan suggested, and consider the general quadratic: ax^2+bx+c=0\tag{1} And develop theorems pertaining to this...
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3 replies | 101 view(s)
06-12-2018,
02:32 PM
MarkFL
replied to a thread
Is 4a^3+5a always a multiple of 3 for positive integers?
in
Intermediate/Advanced Algebra
I would prove this by induction...our hypothesis P_n can be: 4n^3+5n=3k_n We see the base case P_1 is true, and so for our inductive step, we...
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11 replies | 392 view(s)
06-12-2018,
01:47 PM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
One double-angle identity for cosine is: \cos(2\alpha)=2\cos^2(\alpha)-1 If we add 1 to both sides, we get: \cos(2\alpha)+1=2\cos^2(\alpha)...
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20 replies | 632 view(s)
06-12-2018,
11:43 AM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
I took the algebraic steps I needed to get the form indicated. In my first post in this thread, I explained every step taken.
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20 replies | 632 view(s)
06-12-2018,
01:18 AM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
Please use \LaTeX...when I quoted you post, this is what I see (ugh...thumbnails? really?): Finding the needle I wish to address in that...
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20 replies | 632 view(s)
06-11-2018,
11:42 AM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
What about it don't you understand? Are you not familiar with the double angle identities for cosine?
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20 replies | 632 view(s)
06-11-2018,
03:09 AM
MarkFL
replied to a thread
How to calculate B = root A^2 + A^2 + 2AA Cos theta?
in
Geometry and Trig
Okay, let's begin with: B=\sqrt{A^2+A^2+2AA\cos(\theta)} Since AA=A^2 we have: B=\sqrt{A^2+A^2+2A^2\cos(\theta)} Now, A^2+A^2=2A^2, so we...
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20 replies | 632 view(s)
06-10-2018,
04:05 PM
MarkFL
replied to a thread
Absolute Value equations: "if B greater than or equal to 0 then A=B or A=-B"
in
Intermediate/Advanced Algebra
I think you are looking at it correctly. We can have: |\pm6|=6 So, when given: |f(x)|=6 We can solve:
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13 replies | 368 view(s)
06-10-2018,
03:49 PM
MarkFL
replied to a thread
Absolute Value equations: "if B greater than or equal to 0 then A=B or A=-B"
in
Intermediate/Advanced Algebra
To generalize a bit on what I posted before, consider the following: |ax+b|=c Now, if c<0, we know there are no solutions and we are done, so...
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13 replies | 368 view(s)
06-10-2018,
02:49 PM
MarkFL
replied to a thread
Absolute Value equations: "if B greater than or equal to 0 then A=B or A=-B"
in
Intermediate/Advanced Algebra
If I'm given: |6w+18|=6 I would first factor: 6|w+3|=6 Divide through by 6:
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13 replies | 368 view(s)
06-09-2018,
01:50 PM
MarkFL
replied to a thread
Trying to PM Mark (mmm444bot)
in
Administration Issues
Okay, that makes sense then. They were PMs from over a year ago, so any sense of urgency was long ago played out. I was more interested in just...
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1 replies | 190 view(s)
06-09-2018,
01:11 PM
MarkFL
started a thread
Trying to PM Mark (mmm444bot)
in
Administration Issues
Hello! I came back after another long hiatus, and was trying to respond to a couple of PMs from Mark, but I was told his inbox was full. :(
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1 replies | 190 view(s)
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About MarkFL
Basic Information
Date of Birth
October 11, 1963 (54)
About MarkFL
Location:
St. Augustine, FL.
Interests:
Math, Physics, Trombones, Performance Cars, vBulletin Coding
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Living in the pools, They soon forget about the sea...— Rush, "Natural Science" (1980)
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Last Activity
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11:04 PM
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11-24-2012
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