Question 306027
{{{sqrt(12) + sqrt(300)}}}
{{{sqrt(4*3) + sqrt(100*3)}}}
{{{sqrt(4) *sqrt(3) + sqrt(100)*sqrt(3)}}}
{{{2 *sqrt(3) + 10*sqrt(3)}}}
{{{12*sqrt(3)}}}

make sense?
Basically, look for factors in the original numbers 12 and 300 that are squares. Then expand, take the square roots and hope to collect like terms in the result