Question 1075730
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<pre>
{{{x^3 + y^3}}} = {{{144}}}

is equivalent to

{{{(x+y)*(x^2 - xy + y^2)}}} = {{{144}}}.

Replace here (x+y) by 6 (due to the first equation) and cancel both sides by the factor of 6. You will get 

{{{x^2 - xy + y^2}}} = {{{24}}}.

Now, from the first equation express x = 6-y and substitute it into the last equation. You will get

{{{(6-y)^2 -(6-y)*y + y^2}}} = 24.


Simplify and solve this quadratic equation.
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