Evaluate the function $h(x)=x^{4}-4 x^{2}+5$ at the given values of the independent variable and simplify.
a. $h(-2)$
b. $h(-1)$
c. $h(-x)$
d. $h(3 a)$
a. $h(-2)=5$ (Simplify your answer.)
b. $h(-1)=\square$ (Simplify your answer.)
c. $h(-x)=\square$ (Simplify your answer.)
d. $h(3 a)=\square$ (Simplify your answer. $)$

Step 1 ：First, we substitute the given values into the function \(h(x)=x^{4}-4 x^{2}+5\).

Step 2 ：(b) For \(h(-1)\), we substitute \(x=-1\) into the function: \(h(-1)=(-1)^{4}-4(-1)^{2}+5\)

Step 3 ：Calculate the first part: \((-1)^{4}=1\)

Step 4 ：Calculate the second part: \(-4(-1)^{2}=-4\)

Step 5 ：So, \(h(-1)=1-4+5=\boxed{2}\)

Step 6 ：(c) For \(h(-x)\), we substitute \(x=-x\) into the function: \(h(-x)=(-x)^{4}-4(-x)^{2}+5\)

Step 7 ：Calculate the first part: \((-x)^{4}=x^{4}\)

Step 8 ：Calculate the second part: \(-4(-x)^{2}=-4x^{2}\)

Step 9 ：So, \(h(-x)=x^{4}-4x^{2}+5=\boxed{x^{4}-4x^{2}+5}\)

Step 10 ：(d) For \(h(3a)\), we substitute \(x=3a\) into the function: \(h(3a)=(3a)^{4}-4(3a)^{2}+5\)

Step 11 ：Calculate the first part: \((3a)^{4}=81a^{4}\)

Step 12 ：Calculate the second part: \(-4(3a)^{2}=-36a^{2}\)

Step 13 ：So, \(h(3a)=81a^{4}-36a^{2}+5=\boxed{81a^{4}-36a^{2}+5}\)