sketch the graph of the following function. list the coordinates of where extrema or points of inflection…

sketch the graph of the following function. list the coordinates of where extrema or points of inflection occur. state where the function is increasing or decreasing as well as where it is concave up or concave down. f(x)= -x³ + 9x² - 52 d. f is never concave up. f is concave down on (-∞,3) and (3,∞). e. f is concave up on (3,∞). f is concave down on (-∞,3). f. f is concave up on (-∞,3) and (3,∞). f is never concave down. choose the correct graph below.
Answer
Explanation:
Step1: Find the first - derivative
Differentiate $f(x)=-x^{3}+9x^{2}-52$ using the power rule. $f'(x)=-3x^{2}+18x=-3x(x - 6)$.
Step2: Find critical points
Set $f'(x) = 0$. So, $-3x(x - 6)=0$. The critical points are $x = 0$ and $x = 6$.
Step3: Determine intervals of increase and decrease
Test intervals: For $x<0$, let $x=-1$, then $f'(-1)=-3\times(-1)\times(-1 - 6)=-21<0$, so $f(x)$ is decreasing on $(-\infty,0)$. For $0<x<6$, let $x = 1$, then $f'(1)=-3\times1\times(1 - 6)=15>0$, so $f(x)$ is increasing on $(0,6)$. For $x>6$, let $x = 7$, then $f'(7)=-3\times7\times(7 - 6)=-21<0$, so $f(x)$ is decreasing on $(6,\infty)$.
Step4: Find the second - derivative
Differentiate $f'(x)=-3x^{2}+18x$. $f''(x)=-6x + 18=-6(x - 3)$.
Step5: Find inflection point
Set $f''(x)=0$. So, $-6(x - 3)=0$, and the inflection point is at $x = 3$.
Step6: Determine concavity
Test intervals: For $x<3$, let $x = 2$, then $f''(2)=-6\times(2 - 3)=6>0$, so $f(x)$ is concave up on $(-\infty,3)$. For $x>3$, let $x = 4$, then $f''(4)=-6\times(4 - 3)=-6<0$, so $f(x)$ is concave down on $(3,\infty)$.
Answer:
E. f is concave up on $(3,\infty)$. f is concave down on $(-\infty,3)$.