if f(x+2y,x-2y)=xy then f(x,y)=
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Originally Posted by prasum if f(x+2y,x-2y)=xy then f(x,y)= Hint
Use the substitution .
Originally Posted by FernandoRevilla Hint
Use the substitution . can yu please explain me the method
Now, change the name of the variables, by and by .
Originally Posted by prasum can yu please explain me the method You were told to let u= x+ 2y, v= x- 2y. The point of that is that f(x+ 2y, x- 2y)= xy becomes f(u, v)= xy. Now you want to write xy in terms of u and v. Can you solve u= x+ 2y and v= x- 2y for x and y in terms of u and v?
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