Question 318533
this is a perfect square. the more of these you do the more u will start recognizing them
the factor for this is simple, when its a minus sign in the middle theres a + and - in the factors 
{{{(v-3u)(v+3u)}}}
check by foiling
{{{v^2-3uv+3uv-9u^2}}}
{{{v^2-0-9u^2}}}
{{{v^2-9u^2}}}
correct