Let's simplify the left-hand side (LHS) of the equation:
LHS=x−a−bx+a+b+x+a+bx−a−b LHS=(x−a−b)(x+a+b)(x+a+b)2+(x−a−b)2 LHS=x2−(a+b)2x2+a2+b2+2ax+2bx+2ab+x2+a2+b2−2ax−2bx+2ab LHS=x2−(a2+2ab+b2)2x2+2a2+2b2+4ab LHS=x2−a2−2ab−b22x2+2a2+2b2+4ab LHS=x2−a2−2ab−b22(x2+a2+b2+2ab) LHS=x2−(a+b)22(x2+(a+b)2) Now let's simplify the right-hand side (RHS) of the equation:
RHS=x2−a2−2ab−b22(x2−ax−bx+ab)+3(a2+b2) RHS=x2−(a+b)22x2−2ax−2bx+2ab+3a2+3b2 We want to show that LHS=RHS, or x2−a2−2ab−b22(x2+a2+b2+2ab)=x2−a2−2ab−b22x2−2ax−2bx+2ab+3a2+3b2 This is equivalent to:
2(x2+a2+b2+2ab)=2x2−2ax−2bx+2ab+3a2+3b2 2x2+2a2+2b2+4ab=2x2−2ax−2bx+2ab+3a2+3b2 0=a2+b2−2ax−2bx−2ab a2+b2−2ax−2bx−2ab=0 However, we want to find an expression that is always true for all x, a, and b. This equation a2+b2−2ax−2bx−2ab=0 is not generally true. There must be some restrictions in the question for x, a, or b that are not stated. The numerators can be simplified further as follows:
2(x2+(a+b)2)=2x2+2a2+4ab+2b2 2(x2−ax−bx+ab)+3(a2+b2)=2x2−2ax−2bx+2ab+3a2+3b2 Then
2x2+2a2+4ab+2b2=2x2−2ax−2bx+2ab+3a2+3b2 0=a2+b2−2ax−2bx−2ab 0=a2−2a(x+b)+b2−2bx=(a−(x+b))2