Change of variable ODE question.

Question

anonymous · Answer

I'm kinda lost on this one, my plan was to rearrange in terms of y and derive it.

anonymous · Answer

I really struggle with these type of questions, I never know what to do and I end just derving and substituting new variables into the equation and hope for the best...

experimentx · Answer

put y=z - x ... that will cancel a lot of things and simplify problem for you.

anonymous · Answer

I will brainstorm now, so this will be painful, but sometimes it helps *smiles*

Note that what they tell you is something like this.

$$ \frac{dy}{dx}=z^2xe^x-1=xy^2e^x+2x^2ye^x+x^3e^x-1$$

anonymous · Answer

Only following the given instructions

experimentx · Answer

dy/dx = dz/dx - 1 = x(z-x)^2e^x+2x^2(z-x)e^x+x^3e^x - 1

anonymous · Answer

i was working just took time for typing !

experimentx · Answer

@sami-21 what do you use to type those stuff?

anonymous · Answer

Mathtype software!

experimentx · Answer

is this one? http://www.dessci.com/en/products/mathtype/

anonymous · Answer

the name is "Mathtype"
i am using version 6 but later versions are also available.
google it

anonymous · Answer

there was a typo !
correct is

anonymous · Answer

@experimentX  yes you got it . and trial version works for 30 days

anonymous · Answer

@ironictoaster are you ok with this ? did you get it.?

experimentx · Answer

all your equations come in this software ... must be easy than typing latex. nowday i'm using draw instead of latex. thank for info

anonymous · Answer

yw:)

anonymous · Answer

@sami-21 I don't understand where you got -2xz 2nd line after after "we have"

anonymous · Answer

ok

anonymous · Answer

$$\Large (z-x)^2=z^2+y^2-2xz$$

using the formula
$$\Large (a-b)^2=a^2+b^2-2ab$$

got it now !!!

anonymous · Answer

@ironictoaster

anonymous · Answer

Oh right just distributing out the bracket

anonymous · Answer

I don't know how you can these questions I can never do them.

anonymous · Answer

Practice!