Approximate the function at the given value of $x_a,$ using the Taylor polynomial of degree $n=4,$ centered at $c=-2.($Round your answer to four decimal places.$)$

$f(x)=\frac{1}{x^2}$

$P_4=\frac{1}{4}\frac{1}{4}(x2)\frac{3}{16}(x2{)}^2\frac{1}{8}(x2{)}^3\frac{5}{64}(x2{)}^4$

$f(-1\mathrm{.}9)=$