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[golden ore]

Don't know how to answer this

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[ionic shale]

Well use the formula what’s ux and uy?

[golden ore]

I'm not sure

[ionic shale]

Okay well « ux »  denotes the partial derivative of u with respect to x and « uy » with respect to y

[golden ore]

I see

[ionic shale]

so basically ux is calculated by considering y a constant and differentiating only with respect to x

[golden ore]

I need to work out ux and uy and then divide them together right?

[ionic shale]

Yes

[golden ore]

so if I make y = 0 to find x

how do I work out the rest

does that mean x is 1?

ln(0) + x

[ionic shale]

No x and y can be anything you just have to calculate the partial derivative

For example if f(x,y)=x+y^2 then fx(x,y)= 1 and fy(x,y)=2y

In each case you differentiate with respect to one of the two variables

[golden ore]

yes but I don't know how to differentiate log function

ln(y) + x

not sure how to differentiate it

how do I find x and y?

hello

anyone

[ionic shale]

The derivative of ln(x) is 1/x

[golden ore]

i don't get it

HELPPP 😥

[ionic shale]

Here you have u(x,y)=ln(y) +x so ux(x,y) denotes the partial derivative with respect to x so what is the derivative of x+ln(y) with respect to x? (ln(y) is a constant here because it doesn’t depend on x)

uy(x,y) denotes the derivative with respect to y so you consider x a constant and y the variable

Like I said before the derivative of ln(y) is 1/y

[golden ore]

so ln(5) would be 1/5?

[ionic shale]

The derivative of ln(x) evaluated at 5 is 1/5 yes

But the derivative of ln(5) is 0 because it’s a constant

[golden ore]

so if ln(y) = 1/y and x = 1, that means 1/1/y which is y?

so is the answer D

[ionic shale]

Yes

[golden ore]

really?

so the answer to that problem is D

[ionic shale]

Well ln’(y)=1/y

[ionic shale]

Yes because the derivative of x—>x+ln(y) is x—>1 and the derivative of y—>x+ln(y) is y—>1/y

[golden ore]

nice

[ionic shale]

So fx(x,y)/fy(x,y)=1/(1/y)=y

[golden ore]

can I give you another problem

[ionic shale]

Sure it’s your channel you can post if you want

[golden ore]

the best response for Alfonso would be to hunt for deer right?

[ionic shale]

I’ll look at the problem tomorrow I’ve gotta go afk

Im sorry

[golden ore]

ok

[ionic shale]

Good luck anyways

[golden ore]

thanks for your help