choose all that give the correct average rate of change for the specified function on the specified…

choose all that give the correct average rate of change for the specified function on the specified interval. a the average rate of change of f(x)=x² + 2 on 1, 4 is 5. b the average rate of change of f(x)=2x² - 2 on 1, 3 is 4. c the average rate of change of f(x)=4x² + 2 on 0, 3 is 6. d the average rate of change of f(x)=3x² - 1 on 2, 5 is 21.
Answer
Explanation:
Step1: Recall average - rate - of - change formula
The average rate of change of a function $y = f(x)$ on the interval $[a,b]$ is $\frac{f(b)-f(a)}{b - a}$.
Step2: Check option A
For $f(x)=x^{2}+2$ on $[1,4]$, $f(4)=4^{2}+2=16 + 2=18$, $f(1)=1^{2}+2=3$. Then $\frac{f(4)-f(1)}{4 - 1}=\frac{18 - 3}{3}=\frac{15}{3}=5$.
Step3: Check option B
For $f(x)=2x^{2}-2$ on $[1,3]$, $f(3)=2\times3^{2}-2=2\times9 - 2=16$, $f(1)=2\times1^{2}-2=0$. Then $\frac{f(3)-f(1)}{3 - 1}=\frac{16-0}{2}=8\neq4$.
Step4: Check option C
For $f(x)=4x^{2}+2$ on $[0,3]$, $f(3)=4\times3^{2}+2=4\times9 + 2=38$, $f(0)=4\times0^{2}+2=2$. Then $\frac{f(3)-f(0)}{3 - 0}=\frac{38 - 2}{3}=\frac{36}{3}=12\neq6$.
Step5: Check option D
For $f(x)=3x^{2}-1$ on $[2,5]$, $f(5)=3\times5^{2}-1=3\times25 - 1=74$, $f(2)=3\times2^{2}-1=3\times4 - 1=11$. Then $\frac{f(5)-f(2)}{5 - 2}=\frac{74 - 11}{3}=\frac{63}{3}=21$.
Answer:
A. The average rate of change of $f(x)=x^{2}+2$ on $[1,4]$ is 5. D. The average rate of change of $f(x)=3x^{2}-1$ on $[2,5]$ is 21.