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04-25-2009 11:30 PM  9 years agoPost 1


Phoenix, Arizona

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For those RC heli guys who are good at math and remember calc II, we are just starting basic differential equations (separation by variables) and am stuck on these 4 questions

Find the solution to the differential equation below, subject to the initial condition

dB/dt+2B=88; B(1)=140 (I am pulling my hair out on this one)
my current answer is B(t)=(((-192/exp(-.5))exp(-.5t))-88)/(-2)
ANSWER: d(B)=44+96exp(2-2t)

dz/dt=2t(exp(z)); z(0)=0 EDIT: Finally got this one
ANSWER: d(z)=-ln(1-t^2)

dx/dt=(xln(x))/t; x(1)=2 EDIT: Got this one
ANSWER: d(x)=exp(ln(2)t)

x(x+1)du/dx=u^2; u(1)=1 EDIT: Got this one as well
ANSWER: d(u)=-1/(ln(2x/(x+1))-1)

Thanks for.......well, nothing LOL.
Perseverance wins the battle.

04-25-2009 11:47 PM  9 years agoPost 2



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Thanks dude,

Now my brain hurts

Seriously, wish I could help but have not done any calc in 30+ years.

Good luck,

Don't blame me, I did'nt vote for him.

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04-26-2009 02:42 AM  9 years agoPost 3
Peter Wales

rrElite Veteran

Orlando Fl

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I explained this to the cashier in Publix this morning but she still wanted $115 for my groceries rather than the $8 I proved they really cost.

Peter Wales

04-26-2009 02:55 AM  9 years agoPost 4
GimbalFan (RIP)


Big Coppitt Key, FL

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↑↑↑ Bwahahahahahaha! Math humor -- too rare.

I'll guess that regardless of cost, those groceries ALL fit into one bag.


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