a. find the open interval(s) on which the function is increasing and decreasing\nb. identify the functions…

a. find the open interval(s) on which the function is increasing and decreasing\nb. identify the functions local and absolute extreme values, if any, saying where they occur\ng(x)=x\\sqrt{8 - x^{2}}\nd. there are no local maxima.\nfind each local minimum, if there are any. select the correct choice below and, if necessary, fill in the\nanswer box(es) to complete your choice.\n(type an exact answer in simplified form.)\na. the function has a local minimum valuę at one value of x. the minimum value is g()=\nb. the function has a local minimum value at three values of x. in increasing order of x - value, the\nminimum values are g()=, g()=, and g()=\nc. the function has a local minimum value at two values of x. in increasing order of x - value, the\nminimum values are g()= and g()=\nd. there are no local minima.
Answer
Explanation:
Step1: Find the domain of the function
For the function (g(x)=x\sqrt{8 - x^{2}}), the expression under the square - root must be non - negative. So, (8-x^{2}\geq0), which gives (-2\sqrt{2}\leq x\leq2\sqrt{2}).
Step2: Find the derivative of the function
Using the product rule ((uv)^\prime = u^\prime v+uv^\prime), where (u = x) and (v=\sqrt{8 - x^{2}}=(8 - x^{2})^{\frac{1}{2}}). (u^\prime=1) and (v^\prime=\frac{1}{2}(8 - x^{2})^{-\frac{1}{2}}\times(-2x)=\frac{-x}{\sqrt{8 - x^{2}}}) (g^\prime(x)=\sqrt{8 - x^{2}}+x\times\frac{-x}{\sqrt{8 - x^{2}}}=\frac{8 - x^{2}-x^{2}}{\sqrt{8 - x^{2}}}=\frac{8 - 2x^{2}}{\sqrt{8 - x^{2}}})
Step3: Find the critical points
Set (g^\prime(x) = 0), then (\frac{8 - 2x^{2}}{\sqrt{8 - x^{2}}}=0). Since the denominator (\sqrt{8 - x^{2}}\neq0) (because if (\sqrt{8 - x^{2}} = 0), (x=\pm2\sqrt{2}) and the numerator (8 - 2x^{2}\neq0) at (x = \pm2\sqrt{2})), we solve (8 - 2x^{2}=0). (2x^{2}=8), (x^{2}=4), (x=\pm2)
Step4: Analyze the sign of the derivative
- When (-2\sqrt{2}<x<-2), let (x=-3) (not in the domain, but we can test a value close to (- 2\sqrt{2}) and less than (-2), say (x=-2.5) (not in the domain, better to use test points in the domain). Let's use the interval method.
- For the interval ((-2\sqrt{2},-2)), pick (x=-2.5) (invalid, pick (x = - 2.1) (not in the domain). Let's use the fact that (g^\prime(x)=\frac{8 - 2x^{2}}{\sqrt{8 - x^{2}}}). If (x=-2.1) (not in domain, better: when (x=-2), (g^\prime(x) = 0). For (x\in(-2\sqrt{2},-2)), let (x=-2.5) (invalid, use (x=-2.1) (not in domain). Let's use the substitution (y = x^{2}). The function (y = 8 - 2x^{2}) is a parabola opening downwards.
- For (x\in(-2\sqrt{2},-2)), (g^\prime(x)<0) (since (8 - 2x^{2}<0) when (x^{2}>4) and (x\in(-2\sqrt{2},-2))).
- For (x\in(-2,2)), (g^\prime(x)>0) (since (8 - 2x^{2}>0) when (x^{2}<4)).
- For (x\in(2,2\sqrt{2})), (g^\prime(x)<0) (since (8 - 2x^{2}<0) when (x^{2}>4)).
Step5: Find local extrema
- Since the function (g(x)) changes from decreasing ((-2\sqrt{2},-2)) to increasing ((-2,2)), (x=-2) is a local minimum. (g(-2)=-2\sqrt{8 - 4}=-2\times2=-4)
- Since the function (g(x)) changes from increasing ((-2,2)) to decreasing ((2,2\sqrt{2})), (x = 2) is a local maximum. (g(2)=2\sqrt{8 - 4}=4)
Answer:
A. The function has a local minimum value at one value of (x). The minimum value is (g(-2)=-4)