SOLUTION: Given a function f of a real variable which satisfies the function defined by x*f(2-x)-2*f(x)=x^2+1 for all real x, determine f(x) in terms of x.

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Question 1165361: Given a function f of a real variable which satisfies the function defined by x*f(2-x)-2*f(x)=x^2+1 for all real x, determine f(x) in terms of x.
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
Let's make system%28a=f%28x%29%2C+b=f%282-x%29%29

When the variable is x, the equation is
x%2Af%282-x%29-2%2Af%28x%29=x%5E2%2B1 , which we write in abbreviated form as
x%2Ab-2a=x%5E2%2B1 (1)

When the variable is 2-x, the equation is
%282-x%29%2Af%282-%282-x%29%29-2%2Af%282-x%29=%282-x%29%5E2%2B1 , which we want to simplify as
%282-x%29%2Af%28x%29-2%2Af%282-x%29=4-4x%2Bx%5E2%2B1 , and
%282-x%29%2Af%28x%29-2%2Af%282-x%29=x%5E2-4x%2B5 , and abbreviate as
%282-x%29%2Aa-2b=x%5E2-4x%2B5 (2)

In (1) and (2), we have a system of equations on a and b :
system%28x%2Aa-2b=x%5E2-4x%2B5%2C-2a%2Bx%2Ab=x%5E2%2B1%29 . Let's solve for a .

Multiplying (2) times x%2F2 we get %28%282x-x%5E2%29%2F2%29a-%28x%2F2%292b=%28x%2F2%29%28x%5E2-4x%2B5%29 ,
which we simplify to
%28%28-x%5E2%2B2x%29%2F2%29a-x%2Ab=%28x%5E3-4x%5E2%2B5x%29%2F2 ,
and add it to (1) to get
%28%28-x%5E2%2B2x%29%2F2%29a-2a=%28x%5E3-4x%5E2%2B5x%29%2F2%2Bx%5E2%2B1 ,
%28%28-x%5E2%2B2x-4%29%2F2%29a=%28x%5E3-4x%5E2%2B5x%2B2x%5E2%2B2%29%2F2
-x%5E2%2B2x-4=-%28x%5E2-2x%2B4%29 is not zero for any real number,
so we can divide by that expression to solve for a
%28-x%5E2%2B2x-4%29a=%28x%5E3-2x%5E2%2B5x%2B2%29
a=-%28x%5E3-2x%5E2%2B5x%2B2%29%2F%28x%5E2-2x%2B4%29

The function is
highlight%28f%28x%29=-%28x%5E3-2x%5E2%2B5x%2B2%29%2F%28x%5E2-2x%2B4%29%29 .