If f"f(x)=2"ln"(x+1)-ix-xf(x)=2ln(x+1)−ix−x, then f^(-1)(x)f−1(x)is the inverse, or the reflection of f(x)f(x) in the line y=xy=x.
So, let's make f(x)=2"ln"(x+1)-ix-x=0f(x)=2ln(x+1)−ix−x=0, then 2"ln"(x+1)=ix+x=i(2x)2ln(x+1)=ix+x=i(2x), dividing both sides by 2 gives f(x)="ln"(x+1)=(i(2x))/2=ixf(x)=ln(x+1)=i(2x)2=ix.
As e^("ln"(a))=aeln(a)=a, e^(ln(x+1))=x+1=e^(ix)eln(x+1)=x+1=eix.
Now take away (x+1)(x+1) from both sides to make it equal 0, 0=e^(ix)-x+10=eix−x+1.