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 Expanding the numerator and denominator:
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−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−(a2+2ab+b2)2(x2−a(x−b)−b(x−a))+3(a2+b2) RHS=x2−(a+b)22(x2−ax−bx+ab)+3a2+3b2 RHS=x2−(a+b)22(x2−x(a+b)+ab)+3(a2+b2) RHS=x2−(a+b)22x2−2ax−2bx+2ab+3a2+3b2 Now, let us express the numerator as follows:
2x2−2ax−2bx+2ab+3a2+3b2=2x2+2a2+2b2+4ab+a2+b2−2ax−2bx−2ab=2(x2+(a+b)2)+a2+b2−2ax−2bx−2ab However, we cannot obtain the numerator as 2(x2+(a+b)2). Consider the case when x=a+b, then LHS=02(2(a+b)2) which is undefined. Also, RHS=02((a+b)2−a(a+b)−b(a+b)+ab)+3(a2+b2)=02(a2+b2+2ab−a2−ab−ab−b2+ab)+3(a2+b2)=02ab+3(a2+b2). This expression is also undefined. However, we cannot conclude whether the equation is true or false.
Expanding the RHS numerator, we have:
2x2−2ax−2bx+2ab+3a2+3b2=2x2+2(a2+2ab+b2)=2x2+2a2+2b2+4ab only if −2ax−2bx+2ab+3a2+3b2=2a2+2b2+4ab This simplifies to a2+b2−2ax−2bx+2ab=0, i.e., (a+b)2=2x(a+b), or a+b=2x. In this case, the given equation holds. However, this must hold for all x,a,b. Therefore, this is not an identity. The given identity is false in general.