simonthumper
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# 21 Actions

 Apr 23 awarded Commentator Apr 23 comment Solving a problem to do with the partial derivative chain rule. Ahhhhhhh I'm being stupid don't worry... It's neither is it? $f'(x-y) = \frac{\partial f(x-y)}{\partial s}$ ? Apr 23 comment Solving a problem to do with the partial derivative chain rule. Because those are different things so when I do $\frac{\partial^2u}{\partial x \partial y} u$ how do I notate that? Apr 23 comment Solving a problem to do with the partial derivative chain rule. The only problem I have still is with your $'$ notation? What does that mean? is $f'(x-y) = \frac{ \partial f(x-y)}{\partial y}$ or $\frac{ \partial f(x-y)}{\partial x}$? Apr 23 comment Solving a problem to do with the partial derivative chain rule. Ahhhhh right I've got you! Didn't quite click in my mind what you meant until you showed $\frac{\partial}{\partial y}$ Thanks, I'll have another go at it, then mark you correct :D Apr 23 comment Solving a problem to do with the partial derivative chain rule. How do you find $\frac{\partial}{\partial y} u$ Using that method? or $\frac{\partial^2}{\partial x \partial y} u$ ? Apr 23 asked Solving a problem to do with the partial derivative chain rule. Apr 16 accepted Proving formulae for Consecutive population decays. Apr 13 answered Proving formulae for Consecutive population decays. Apr 13 comment Proving formulae for Consecutive population decays. Ok I've followed your method, however even the way your saying to do it doesn't account for the $\alpha A_0 \frac{e^{−\alpha t}−e^{−\beta t}}{\beta − \alpha}$ because you don't get the $e^{-\beta t}$ in the numerator... :/ Apr 12 comment Proving formulae for Consecutive population decays. Oooop, just realised I'm being stupid... One second! Apr 12 comment Proving formulae for Consecutive population decays. This is confusing me soooo much! I've only ever done particular solutions and general solutions for second order DE's, for first order I've only ever done using integrating factors, but that doesn't work in this case because you don't know what B is, so you can't use it as an integrating factor! :/ Graghhh I'm soooo frustrated with this question :/ Apr 12 comment Proving formulae for Consecutive population decays. Will I need to use an integrating factor to get the particular solution? Apr 12 asked Proving formulae for Consecutive population decays. Apr 12 accepted Evaluation of $\lim_{ x \to \infty} x^{\frac{3}{2}}(\sqrt{x+2}-2\sqrt{x+1}+\sqrt{x})$ Mar 30 comment Evaluation of $\lim_{ x \to \infty} x^{\frac{3}{2}}(\sqrt{x+2}-2\sqrt{x+1}+\sqrt{x})$ Ahhh dammit why can't I spot these things for myself! :P Mar 30 awarded Supporter Mar 30 awarded Scholar Mar 29 awarded Student Mar 29 asked Evaluation of $\lim_{ x \to \infty} x^{\frac{3}{2}}(\sqrt{x+2}-2\sqrt{x+1}+\sqrt{x})$