Concept:
A root \(\alpha\) of multiplicity \(m\) satisfies
\[
(x-\alpha)^m
\]
as a factor of the polynomial.
To find the multiplicity, factorize the polynomial completely.
Step 1: Factorize the given polynomial.
Given
\[
P(x)=x^4-4x^3+16x-16.
\]
Grouping terms,
\[
P(x)
=
x^3(x-4)+4(x-4).
\]
Taking the common factor \((x-4)\),
\[
P(x)
=
(x-4)(x^3+4).
\]
Using
\[
a^3+b^3=(a+b)(a^2-ab+b^2),
\]
we get
\[
x^3+4
=
x^3+2^3
=
(x+2)(x^2-2x+4).
\]
Hence,
\[
P(x)
=
(x-4)(x+2)(x^2-2x+4).
\]
Step 2: Check the multiplicity of the roots.
The factors
\[
(x-4),\quad (x+2),\quad (x^2-2x+4)
\]
all occur only once.
Therefore, every root of the equation has multiplicity
\[
m=1.
\]
Step 3: Evaluate \(m^2-4m+2\).
Substituting \(m=1\),
\[
m^2-4m+2
=
1^2-4(1)+2.
\]
\[
=1-4+2.
\]
\[
=-1.
\]
Step 4: Write the final answer.
\[
\boxed{-1}
\]