Answer
a. $12(t+2)(t-2)$
b. $3(2x+1)^{2}$
Work Step by Step
a.
$12t^{2}-48=$
...factor out the GCF, $12$.
$=12(t^{2}-4)$
...write the difference as $a^{2}-b^{2}$.
$=12(t+2)(t-2)$
b.
$12x^{2}+12x+3=$
...factor out the GCF, $3$.
$=3(4x^{2}+4x+1)$
...write as the square of a binomial
$=3(2x+1)^{2}$