Answer
$(2t-3s)(2t+3s)$
Work Step by Step
RECALL:
$A^2-B^2=(A-B)(A+B)$
The given binomial can be written as:
$=2^2t^2-3^2s^2
\\=(2t)^2-(3s)^2$
Factor the binomial using the formula above with $A=2t$ and $B=3s$ to obtain:
$=(2t-3s)(2t+3s)$