The slope of the line normal to the curve e^x-x^3+y^2=10 at the point (0,3) is:
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OpenStudy (mathmusician):
OpenStudy (mathmusician):
There is an easier way to see the question.
OpenStudy (therawbugeyes):
do u still need help
OpenStudy (mathmusician):
Yes
OpenStudy (mathmusician):
@therawbugeyes
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OpenStudy (s4sensitiveandshy):
Implicit differentiation
OpenStudy (s4sensitiveandshy):
take the derivative of the given equation with respect to x. And then substitute (x,y) with (0,3)
OpenStudy (mathmusician):
OKay
OpenStudy (mathmusician):
Would the derivative be \[e ^{x}-3x ^{2}\]
OpenStudy (s4sensitiveandshy):
looks good so far
with respect to x so \[e^x -3x^2 \frac{dx}{dx}\]
dx cancels out so left with e^x-3x^2
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OpenStudy (mathmusician):
What happened to the y
OpenStudy (s4sensitiveandshy):
take the derivative of y. the term y^2 is the part of left side expression.
OpenStudy (mathmusician):
Could you write that out for me please?
OpenStudy (s4sensitiveandshy):
\[e^x -3x^2 +2y \frac{dy}{dx}=0\]
derivative of constant =0
now solve for dy/dx
OpenStudy (mathmusician):
ummm do i just move it to the other side?(Divide)
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OpenStudy (s4sensitiveandshy):
hmm well what would you divide ?
OpenStudy (mathmusician):
The dy/dx
OpenStudy (s4sensitiveandshy):
if you divide first by dy/dx
you have to divide all terms at left side by dy/dx
\[\frac{e^x}{dy/dx} -\frac{3x^2}{dy/dx} +2y =0\]
like this.
looks messssy
OpenStudy (s4sensitiveandshy):
first move (e^x-3x^2) to the right side. move all the terms except dy/dx from left side.
OpenStudy (mathmusician):
okay so it would look \[\frac{ dy }{ dx } = -(e ^{x}-3x ^{2})\]like
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OpenStudy (s4sensitiveandshy):
hmm what about 2y ?? what did you do with that ?
OpenStudy (s4sensitiveandshy):
it should be \[2y\frac{ dy }{ dx } = -(e ^{x}-3x ^{2})\]
divide both sides.
OpenStudy (mathmusician):
\[\frac{ dy }{ dx }=-(e ^{x}-3x ^{2}+2y)\]
OpenStudy (s4sensitiveandshy):
nahh i said divide
2y times dy/dx
^mutiplication
do the opposite of multiplication to cancel out 2y.
Don't
OpenStudy (s4sensitiveandshy):
don't forget simple math :P
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