Question 1209394
<pre>
As the last tutor showed, 

{x,y} = {3,-1} and x<sup>2</sup> + y<sup>2</sup> = 9 + 1 = 10

What the student should observe here is that 

All REAL numbers ARE COMPLEX numbers!

3 and -1 are complex numbers because they are 3 + 0i and -1 + 0i respectively.

Nobody said the coefficient of " i " cannot be 0. And if it's 0, the number
is still complex.  It's both REAL and COMPLEX.

Edwin</pre>