Find the domain for the particular solution to the differential equation dy dx equals the quotient of negative 1 times x and y, with initial condition y(2) = 2.
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It's cool. I appreciate you taking your time to read the question.
OpenStudy (anonymous):
@freckles Would you happen to know?
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OpenStudy (freckles):
first find when when dy/dx does not exist
note dy/dx is -x/y
and -x/y is fine unless ....?
OpenStudy (freckles):
think fractions are not cool if the bottom is ...
OpenStudy (anonymous):
0
OpenStudy (freckles):
right we don't want y to be 0...
now we need to keep this in mind after we solve the differential
equation we will try to use this
so what do you get when you solve dy/dx=-x/y
OpenStudy (anonymous):
I got \[y = \sqrt{\frac{ -x^2 }{ 4 }+5}\]
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OpenStudy (freckles):
not sure how you got the 5...
\[y dy=-x dx \\ \frac{y^2}{2}=\frac{-x^2}{2}+C \\ \text{ I would \not attempt \to solve for } y \text{ yet } \\ \text{ but I'm going \to use the condition given \to find } C \\ \frac{2^2}{2}=\frac{-2^2}{2}+C \\ \frac{2(2)^2}{2}=C \\ C=2^2=4 \\ \frac{y^2}{2}=\frac{-x^2}{2}+4 \\ y^2=-x^2+8 \\ \text{ but } y \neq 0 \\ \text{ so } -x^2+8 \neq 0 \text{ when ? }\]
OpenStudy (anonymous):
What are you asking exactly?
OpenStudy (freckles):
for what x is -x^2+8=0?
OpenStudy (anonymous):
\[\sqrt{8}\]
OpenStudy (freckles):
or?
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OpenStudy (anonymous):
-\[\sqrt{8}\]
OpenStudy (freckles):
|dw:1449725022181:dw|
OpenStudy (anonymous):
-2sqrt(2) to 2sqrt(2)
OpenStudy (freckles):
right
OpenStudy (anonymous):
Thanks
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