Form the conjugate of the denominator by the rule:

the conjugate of A + B is A - B.  You just change the sign
of the second term but keep the sign of the first term.

So the conjugate of the denominator  is
.

Put this conjugate over itself like this: .

Since that red fraction just equals 1 we can multiply our express
by it and not change its numerical value, but change its form. So we multiply
by it:

×.

We'll put parentheses around the binomials:

×.


And multiply numerators and denominators:
















To get the negative sign off the bottom, bring it to the top:


 
We can multiply the negative sign into the parentheses so it won't
be sticking out in front:



Finally we will reverse the terms in the parentheses:



That's the simplest form.  Or this way



Edwin