Taylor Expansion: Wondering Which is Right?

[mathmari]

Hey!

I want to find the taylor expansion of $f(x, y)=x^2 (3y-2x^2)-y^2 (1-y)^2$ at the point $(0, 1)$ and I got the following:

$$f(x, y)=3x^2-(y-1)^2+3x^2 (y-1)-2 (y-1)^3-2x^4-(y-1)^4$$

but a friend of mine got the following result:

$$f(x, y)=3x^2-(y-1)^2+3x^2 (y-1)+3x (y-1)^2+2(y-1)^3-2x^4-(y-1)^4$$

which of them is the right one?? (Wondering)

 

[I like Serena]

Hey!

I want to find the taylor expansion of $f(x, y)=x^2 (3y-2x^2)-y^2 (1-y)^2$ at the point $(0, 1)$ and I got the following:

$$f(x, y)=3x^2-(y-1)^2+3x^2 (y-1)-2 (y-1)^3-2x^4-(y-1)^4$$

but a friend of mine got the following result:

$$f(x, y)=3x^2-(y-1)^2+3x^2 (y-1)+3x (y-1)^2+2(y-1)^3-2x^4-(y-1)^4$$

which of them is the right one?? (Wondering)

Hi! (Wave)

According to Wolfram f(x,y) is equal to your expansion, but it is not equal to the second expansion.

So I believe your expansion is the right one. (Nod)

 

[mathmari]

Hi! (Wave)

According to Wolfram f(x,y) is equal to your expansion, but it is not equal to the second expansion.

So I believe your expansion is the right one. (Nod)

Great! Thank you! (Smile)