#### Answer

$-3a^4+5a^2-1.2$

#### Work Step by Step

Since the expression in parenthesis is preceded by a negative sign, then all terms inside the parenthesis will alter its sign when the parenthesis is removed. Hence, the given expression, $
-(3a^4-5a^2+1.2)
$, is equivalent to
\begin{array}{l}
-3a^4+5a^2-1.2
.\end{array}