Problem

Suppose $f(x)=\left\{\begin{array}{l}x^{2}-4 x \text { for } x<-4 \\ 4 x-x^{2} \text { for } x \geq-4\end{array}\right.$ then \[ \int_{-16}^{4} f(x) d x \] is equal to... $\int_{-16}^{-4}\left(x^{2}-4 x\right) d x+\int_{-4}^{4}\left(4 x-x^{2}\right) d x$ B. $\int_{-16}^{0}\left(x^{2}-4 x\right) d x+\int_{0}^{4}\left(4 x-x^{2}\right) d x$ C. $\int_{-16}^{-4}\left(4 x-x^{2}\right) d x+\int_{-4}^{4}\left(x^{2}-4 x\right) d x$ D. $\int_{-16}^{-4}\left(x^{2}-4 x\right) d x+\int_{-4}^{4}\left(x^{2}-4 x\right) d x$ E. $\int_{-16}^{0}\left(4 x-x^{2}\right) d x+\int_{0}^{4}\left(x^{2}-4 x\right) d x$

Solution

Step 1 :Suppose the function $f(x)$ is defined as $\left\{\begin{array}{l}x^{2}-4 x \text { for } x<-4 \\ 4 x-x^{2} \text { for } x \geq-4\end{array}\right.$

Step 2 :We want to find the integral of $f(x)$ from -16 to 4, which is $\int_{-16}^{4} f(x) d x$

Step 3 :We split the integral into two parts: from -16 to -4 and from -4 to 4

Step 4 :For the first part, we use the function $x^{2}-4 x$, so the integral from -16 to -4 is $\int_{-16}^{-4}\left(x^{2}-4 x\right) d x$

Step 5 :For the second part, we use the function $4 x-x^{2}$, so the integral from -4 to 4 is $\int_{-4}^{4}\left(4 x-x^{2}\right) d x$

Step 6 :Therefore, the integral of $f(x)$ from -16 to 4 is $\int_{-16}^{-4}\left(x^{2}-4 x\right) d x+\int_{-4}^{4}\left(4 x-x^{2}\right) d x$

Step 7 :The integral of the first part is 1824

Step 8 :The integral of the second part is $-\frac{128}{3}$

Step 9 :Adding these two integrals together, we get the final integral is $\frac{5344}{3}$

Step 10 :Final Answer: The integral of the function $f(x)$ from -16 to 4 is $\boxed{\frac{5344}{3}}$

From Solvely APP
Source: https://solvelyapp.com/problems/38135/

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