Question 1072669
<pre>
I changed the numbers.  But the steps are the same.  

{{{system(x^2+y^2=45,(x+y)^2=81)}}}

{{{(x+y)^2=81)}}}

{{{x^2+2xy+y^2=81)}}}

{{{x^2+y^2+2xy=81)}}}

{{{(x^2+y^2)+2xy=81)}}}

Substitute 45 from the other equation for x<sup>2</sup>+y<sup>2</sup>:

{{{45+2xy=81)}}}

{{{2xy=36}}}

{{{xy=18}}}

{{{y=18/x}}}

Substitute in 

{{{x^2+y^2=45}}}

{{{x^2+(18/x)^2=45}}}

{{{x^2+324/x^2=45}}}

{{{x^4+324=45x^2}}}

{{{x^4-45x^2+324=0}}}

{{{(x^2-9)(x^2-36)=0}}}

{{{(x-3)(x+3)(x-6)(x+6)=0}}}

x-3=0; x+3=0;  x-6=0;  x+6=0
  x=3;   x=-3;   x=6;   x=-6

Use this as a model to do yours.

Edwin</pre>