Question 453389
{{{3n^2-75=0}}}, divide by 3
{{{n^2-25=0}}}, express 25 as a full square of 5
{{{n^2-5^2=0}}}, factorize difference of the two full squares
{{{(n+5)(n-5)=0}}}
:
Now it can be
{{{n+5=0}}} -> n=-5
{{{n-5=0}}} -> n=5