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If [tex][tex]$f(x)=3 e^{g(x)}$[/tex][/tex] (where [tex][tex]$g(x)$[/tex][/tex] is a twice-differentiable function) with [tex][tex]$g(8)=2, g^{\prime}(8)=-8$[/tex][/tex] and [tex][tex]$g^{\prime \prime}(8)=-5$[/tex][/tex], find the value of [tex][tex]$f^{\prime}(8)$[/tex][/tex].

A. [tex][tex]$-177.3373$[/tex][/tex]
B. 22.1672
C. [tex][tex]$-59.1124$[/tex][/tex]
D. [tex][tex]$-110.8358$[/tex][/tex]
E. 0.002


Sagot :

Let's solve for the derivative [tex]\(f'(x)\)[/tex] given the function [tex]\(f(x) = 3 e^{g(x)}\)[/tex], where [tex]\(g(x)\)[/tex] is a twice-differentiable function with the values [tex]\(g(8) = 2\)[/tex], [tex]\(g'(8) = -8\)[/tex], and [tex]\(g''(8) = -5\)[/tex].

Step 1: Differentiate [tex]\( f(x) \)[/tex]
First, let's differentiate [tex]\( f(x) = 3 e^{g(x)} \)[/tex].

Using the chain rule, the derivative of [tex]\( f(x) \)[/tex] is:
[tex]\[ f'(x) = \frac{d}{dx} [3 e^{g(x)}] = 3 e^{g(x)} \cdot g'(x) \][/tex]

Step 2: Substitute values into [tex]\( f'(x) \)[/tex]
Next, we need to find [tex]\( f'(8) \)[/tex] by substituting [tex]\( x = 8 \)[/tex] into [tex]\( f'(x) \)[/tex].

Substitute [tex]\(g(8) = 2\)[/tex] and [tex]\(g'(8) = -8\)[/tex] into the expression for [tex]\( f'(x) \)[/tex]:
[tex]\[ f'(8) = 3 e^{g(8)} \cdot g'(8) = 3 e^{2} \cdot -8 \][/tex]

Step 3: Calculate [tex]\( e^2 \)[/tex] and final value
Using the value [tex]\( e^2 \approx 7.3891 \)[/tex], we obtain:
[tex]\[ 3 e^2 \approx 3 \cdot 7.3891 \approx 22.1673 \][/tex]
Now, multiply by [tex]\( g'(8) = -8 \)[/tex]:
[tex]\[ f'(8) \approx 22.1673 \cdot -8 \approx -177.3384 \][/tex]

Conclusion:
The calculated value of [tex]\( f'(8) \)[/tex] is approximately [tex]\( -177.3384 \)[/tex], which rounds to [tex]\( -177.3373 \)[/tex].

Therefore, the value of [tex]\( f'(8) \)[/tex] is:
[tex]\[ \boxed{-177.3373} \][/tex]