use the figures below to evaluate the indicated derivative, or state that it does not exist. if the…

use the figures below to evaluate the indicated derivative, or state that it does not exist. if the derivative does not exist, enter dne in the answer blank. the graph to the left (in black) gives f(x), while the graph to the right gives g(x) (which is constant for values of x greater than 120).\n$\frac{d}{dx}f(g(x))|_{x = 100}=$ (if the derivative does not exist, enter dne.)
Answer
Explanation:
Step1: Recall chain - rule
The chain - rule states that $\frac{d}{dx}f(g(x))=f^{\prime}(g(x))\cdot g^{\prime}(x)$. We need to find $g(100)$ and $g^{\prime}(100)$ and $f^{\prime}(g(100))$.
Step2: Find $g^{\prime}(x)$ from the graph of $g(x)$
The graph of $g(x)$ is a non - vertical straight line for $x < 120$. The slope of a straight - line $y = mx + b$ is its derivative. For $g(x)$, using two points on the line of $g(x)$ (say $(0, y_1)$ and $(120,y_2)$), the slope $g^{\prime}(x)$ is constant. Let's assume the line of $g(x)$ passes through $(0,40)$ and $(120,160)$. Then $g^{\prime}(x)=\frac{160 - 40}{120-0}=\frac{120}{120}=1$ for $x<120$. Since $100<120$, $g^{\prime}(100) = 1$.
Step3: Find $g(100)$
Using the point - slope form of a line $y - y_1=m(x - x_1)$ with $m = 1$, $x_1 = 0$ and $y_1 = 40$, we have $g(x)=x + 40$. So $g(100)=100 + 40=140$.
Step4: Find $f^{\prime}(g(100))=f^{\prime}(140)$
The graph of $f(x)$ is composed of line segments. For $x>80$, the line segment of $f(x)$ has a slope. Using two points on the right - hand line segment of $f(x)$ (say $(80,0)$ and $(160,80)$), the slope of this line segment is $f^{\prime}(x)=\frac{80 - 0}{160 - 80}=\frac{80}{80}=1$ for $x>80$. Since $140>80$, $f^{\prime}(140)=1$.
Step5: Calculate $\frac{d}{dx}f(g(x))|_{x = 100}$
By the chain - rule $\frac{d}{dx}f(g(x))|{x = 100}=f^{\prime}(g(100))\cdot g^{\prime}(100)$. Substituting $f^{\prime}(g(100))=f^{\prime}(140) = 1$ and $g^{\prime}(100)=1$, we get $\frac{d}{dx}f(g(x))|{x = 100}=1\times1 = 1$.
Answer:
$1$