Calculus1
8 Online
OpenStudy (anonymous):
i think i figured this equation out but i need someone to check it.
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OpenStudy (anonymous):
\[xe ^{y} + 1 = xy\]
OpenStudy (anonymous):
\[\frac{ xe ^{y} + 1 }{ x} = y\]
OpenStudy (anonymous):
\[xe ^{y} + 1 \times (x ^{-1})\]
OpenStudy (anonymous):
\[(xe ^{y} + 1) (-1) + (x^{-1})(xe^{y} + 0)\]
OpenStudy (anonymous):
\[-(xe^{y} + 1 ) + (x^{-1})(xe^{y})\]
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OpenStudy (anonymous):
i dont understand wht u need to do on that equation?
OpenStudy (anonymous):
finding the derivative.
OpenStudy (anonymous):
\[(-xe^{y} -1) + (x^{-1})(xe^{y} + 0)\]
OpenStudy (anonymous):
well i really dont understood, sorry, do u know implicit diferentiation?
OpenStudy (anonymous):
we've done it in class but i don't remember how to do it.
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OpenStudy (anonymous):
i think that the way to do this is by implicit diferentiation
OpenStudy (anonymous):
i dont understodd the method that u used to solve this
OpenStudy (anonymous):
which metod it was
OpenStudy (anonymous):
the chain rule to differentiate.
OpenStudy (anonymous):
i really dont understad what u did
if u could explaint me each step
or we can try with implicit diferentiation
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OpenStudy (anonymous):
try the implicit differentiation
OpenStudy (anonymous):
we have this
xe^y +1=xy
OpenStudy (anonymous):
okay
OpenStudy (anonymous):
u remember the product rule right?
OpenStudy (anonymous):
first times the dx/dy of the second plus second times the dx/dy of the first?
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OpenStudy (anonymous):
yes lets work with just this part
xe^y
i meant the firts term
OpenStudy (anonymous):
u got it?
OpenStudy (anonymous):
which is ...\[x(e^{y}) + e^{y} (1) + 0\]
OpenStudy (anonymous):
yes but u must get the derivative of (y) too
OpenStudy (anonymous):
and put it where?
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OpenStudy (anonymous):
x(e^y)(dy/dx)+ey(1)+0
OpenStudy (anonymous):
x(e^y)(dy/dx)+e^y(1)+0
OpenStudy (anonymous):
did u get it?
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
remember the original equation equation
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OpenStudy (anonymous):
xe^y +1=xy
OpenStudy (anonymous):
now lets work with the (xy)
OpenStudy (anonymous):
i meant the right part of the equation
OpenStudy (anonymous):
ok
OpenStudy (anonymous):
are u following me?
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OpenStudy (anonymous):
ok could u apply the product rule on
xy
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
x(dy) + y(dx)
OpenStudy (anonymous):
i m not sure about that
OpenStudy (anonymous):
xy´ + yx´
that is what we r trying to find
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OpenStudy (anonymous):
okay
OpenStudy (anonymous):
is that right?
OpenStudy (anonymous):
ok but y´ = dy/dx
and x´=1
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
do u got that?
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OpenStudy (anonymous):
how come x isn't dx/dy
OpenStudy (anonymous):
sorry x'
OpenStudy (anonymous):
we r trying to find the derivative with respect to the variable x
OpenStudy (anonymous):
so for y we have y´ = dy/dx
OpenStudy (anonymous):
and for x we have x´ = dx/dx = 1
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OpenStudy (anonymous):
ohh okay
OpenStudy (anonymous):
so lets write the derivative of xy
OpenStudy (anonymous):
x + y(dy/dx)
OpenStudy (anonymous):
well no
OpenStudy (anonymous):
again with the product rule we have
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OpenStudy (anonymous):
x´y + xy´
OpenStudy (anonymous):
x´ = 1
y´ =dy/dx
OpenStudy (anonymous):
y + x(dy/dx)
OpenStudy (anonymous):
yes now lets put all the parts together in the original equation
xe^y +1=xy
OpenStudy (anonymous):
could u do that
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OpenStudy (anonymous):
\[x(e^{y})\frac{ dy }{ dx} + e^{y} = y + x(\frac{ dy }{ dx })\]
OpenStudy (anonymous):
that is right
now we must solve for dy/dx
OpenStudy (anonymous):
do u know how to do that?
OpenStudy (anonymous):
i can trytry
OpenStudy (anonymous):
ok
will be wathching
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OpenStudy (anonymous):
jajaaj bad english
OpenStudy (anonymous):
\[\frac{ e^{y}-y }{ x-xe^{y}}=\frac{ dy }{ dx}\]
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
so it is done
OpenStudy (anonymous):
could you you help me on one more?
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OpenStudy (anonymous):
ok i will try
OpenStudy (anonymous):
\[\int\limits \frac{ e^\sqrt{x} }{ \sqrt{x}} dx\]
OpenStudy (anonymous):
have u tried u-substitution?
OpenStudy (anonymous):
i thought so,but im not sure if i use square root of x
OpenStudy (anonymous):
yes\[u=\sqrt{x}\]
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OpenStudy (anonymous):
now lets find du/dx
OpenStudy (anonymous):
-1/2x^1/2
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
so we multiply by 1/2
OpenStudy (anonymous):
or e?
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OpenStudy (anonymous):
e?
OpenStudy (anonymous):
im stuck right theere
OpenStudy (anonymous):
lets write it with the diferentials
OpenStudy (anonymous):
what you mean?
OpenStudy (anonymous):
du= \[\frac{ 1 }{ 2\sqrt{x} }\]dx
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OpenStudy (anonymous):
i don't understand
OpenStudy (anonymous):
\[du = \frac{ 1 }{ 2\sqrt{x} }dx\]
OpenStudy (anonymous):
do u get it now?
OpenStudy (anonymous):
so its not ..\[-\frac{ 1 }{ 2 }x^{\frac{ 1 }{ 2 }}\]dx
OpenStudy (anonymous):
no
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OpenStudy (anonymous):
remember the power rule for derivatives
OpenStudy (anonymous):
okay
OpenStudy (anonymous):
so u know the reason?
OpenStudy (anonymous):
not sure,but your du = my du i just got rid of the radical sign and the fraction
OpenStudy (anonymous):
wait .. aren't i suppose to subtract one fro the exponent when i bring it to the front?
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OpenStudy (anonymous):
yes
OpenStudy (anonymous):
so .. what did i do wrong?
OpenStudy (anonymous):
the power rule is
\[d x^{n}/dx = nx ^{n-1}\]