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mathcalculus
Group Title
hello guys, can someone help me with related rates?
(attached)
 one year ago
 one year ago
mathcalculus Group Title
hello guys, can someone help me with related rates? (attached)
 one year ago
 one year ago

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Psymon Group TitleBest ResponseYou've already chosen the best response.0
Eww, word problems *waits for the problem and prepares sword*
 one year ago

Psymon Group TitleBest ResponseYou've already chosen the best response.0
Oh, not a word problem :D okay, np with this one
 one year ago

Psymon Group TitleBest ResponseYou've already chosen the best response.0
So whenever you take the derivative of y, you can mark it with (dy/dx). Whenever you take the derivative of an x, you can mark it with (d/dx). So take the derivative of both sides, put dy/dx and d/dx where necessary, and plug in the given values.
 one year ago

zzr0ck3r Group TitleBest ResponseYou've already chosen the best response.1
the derivative of 7x^3  10x with respect to t Is 0
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
dx/dt = 0 so will dy/dt
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
alright let me try this step by step.
 one year ago

zzr0ck3r Group TitleBest ResponseYou've already chosen the best response.1
y is in terms of x, there are no t's so treat x's like a constant derivative of a constant is 0
 one year ago

Psymon Group TitleBest ResponseYou've already chosen the best response.0
Pretty much. They made it a little easy on ya with there being a dx/dt, haha. But itd be nice practice if we said it was d/dx and made d/dx equal to 1.
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
okay so the derivative to this would be: 21x^210
 one year ago

zzr0ck3r Group TitleBest ResponseYou've already chosen the best response.1
with respect to x, yes but they ask for it with respect to t (not x)
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
okay. so do i multiply each by dx/dt?
 one year ago

Psymon Group TitleBest ResponseYou've already chosen the best response.0
Its like theyre saying, there is no t for there to be a derivative in respect to, so everything is 0. Thats why I said we should change the conditions of the problem for practice.
 one year ago

zzr0ck3r Group TitleBest ResponseYou've already chosen the best response.1
\[\frac{d(f(x))}{dt}=0\]
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
x is some function of t, thus when we take the derivative of y with respect to t, we get \[\frac{ dy }{ dt }=\frac{ d }{ dt }\left( 7x ^{3}10x \right)=\frac{ d }{ dt }\left( 7x ^{3} \right)\frac{ d }{ dt }\left( 10x \right)=21x ^{2}\frac{ dx }{ dt }10\frac{ dx }{ dt }\]form there it's plug in what you know and compute
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
since dx/dt is 0, dy/dt is 0. y only depends on x. look at te function. if x doesn't change, neither will y. the math proves it.
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
question: why would it be zero?
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
the problem states that dx/dt = 0
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
each term in dy/dt is multiplied by dx/dt
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
and dy/dt= d/dt?
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
no, d/dt is an operator. it says take the derivative of wht follows with respect to t.
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
dy/dt is the derivative of y with respect to t.
 one year ago

pgpilot326 Group TitleBest ResponseYou've already chosen the best response.1
do you know the chain rule for derivatives?
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
sort of, I need to refresh my memory with the chain rule.
 one year ago
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