Problem

Given the Taylor polynomial for $f(x)$ at $x=3$, find $f^{(4)}(3)$ :
\[
\begin{array}{l}
T_{4}(x)=2+x-3+(x-3)^{2}+(x-3)^{3}-2(x-3)^{4} \\
f^{(4)}(3)=99
\end{array}
\]

Answer

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Answer

\(\boxed{f^{(4)}(3) = -48}\)

Steps

Step 1 :Given the Taylor polynomial for \(f(x)\) at \(x=3\):

Step 2 :\(T_{4}(x)=2+(x-3)+1(x-3)^{2}+1(x-3)^{3}-2(x-3)^{4}\)

Step 3 :The coefficients of the Taylor polynomial represent the derivatives of \(f(x)\) at \(x=3\) divided by the corresponding factorial:

Step 4 :\(f(3) = 2\)

Step 5 :\(f'(3) = 1\)

Step 6 :\(f''(3) = 1 \cdot 2\)

Step 7 :\(f'''(3) = 1 \cdot 3!\)

Step 8 :\(f^{(4)}(3) = -2 \cdot 4!\)

Step 9 :Calculate \(f^{(4)}(3)\):

Step 10 :\(f^{(4)}(3) = -2 \cdot 4! = -2 \cdot 24 = -48\)

Step 11 :\(\boxed{f^{(4)}(3) = -48}\)

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