Maclaurin series question help: f(x)= (1-x)^-1 up to the term in x^3

[K622338]

I'm trying to solve f(x)= (1-x)^-1 up to the term in x^3 . I got
1-x+x^2-x^3
but my teacher says this is wrong

 

[tkhunny]

I'm trying to solve f(x)= (1-x)^-1 up to the term in x^3 . I got
1-x+x^2-x^3
but my teacher says this is wrong

Have to agree with your teacher. You created 1/(1+x). Must be missing a sign consistently.