In the complex number 'realm', for a complex number to be considered equal to , then both it's real and imaginary parts must be equal to zero!

Hence and for

So let's look at the case where . For this and , which means that . So the first equation is satisfied. . So the 2nd is satisfied.

Now look at the case where . For this c=0 and d = 0, which means that . So the first equation is satisfied. . So the 2nd is satisfied.