Since there's no real good way of solving this problem, let's just expand each one of the expressions. I will use foil because it's easiest for me.
The one you have selected:
[tex](x+5-6i)(x+5-6i) = x^2+5x-6ix+5x+25-30i-6ix-30i-36[/tex]
[tex]x^2+10x-12ix-11-60i[/tex]
NOT CORRECT
3rd Option:
[tex](x+5-6i)(x-5+6i) = x^2-5x+6ix+5x[/tex]
We can already see that this would simplify with no x's (5x-5x=0) and out equation has 10x in it. So, this is NOT CORRECT.
4th Option:
[tex](x+5-6i)(x+5+6i)=x^2+5x+6ix+5x+25+30i-6ix-30i+36[/tex]
[tex]x^2+10x+61[/tex]
NOT CORRECT.
So, the correct option has to be the 1st Option. Hope this helps buddy!
