Try the fastest way to create flashcards
Question

Determine the location and value of the absolute extreme values of f on the given interval, if they exist. f(x)=3x2/3x on [0,27]f(x)=3 x^{2 / 3}-x \text { on }[0,27]

Solution

Verified
Step 1
1 of 2

Differentiating f(x)=3x23xf(x)=3x^{\frac{2}{3}}-x on [0,27][0,27], we have

f(x)=323x2311=2x131=2x31\begin{align*} f'(x)&= 3\cdot \frac{2}{3}x^{\frac{2}{3}-1}-1\\ &=2x^{-\frac{1}{3}}-1\\ &=\dfrac{2}{\sqrt[3]{x}}-1 \end{align*}

To find the critical points, we solve the equation f(x)=0f'(x)=0 and we search for values where f(x)f'(x) is undefined.

f(x)=02x31=02x3=1x3=2x=8\begin{gather*} f'(x)=0\\ \dfrac{2}{\sqrt[3]{x}}-1=0\\ \dfrac{2}{\sqrt[3]{x}}=1\\ \sqrt[3]{x}=2\\ x=8 \end{gather*}

Also, at x=0x=0, f(x)f'(x) is undefined. [10pt] These two critical points and the endpoints are candidates for the location of the absolute extrema.

The next step is to evaluate ff at the critical points and endpoints.

f(0)=30230=0f(8)=38238=4f(27)=3272327=0\begin{align*} f(0)=3\cdot0^{\frac{2}{3}}-0=0\\ f(8)=3\cdot8^{\frac{2}{3}}-8=4\\ f(27)=3\cdot27^{\frac{2}{3}}-27=0\\ \end{align*}

The largest of these function values is f(8)=4f(8)=4, which is the absolute maximum value of ff on [0,27][0,27]. The least of these values is f(0)=f(27)=0f(0)=f(27)=0, which is the absolute minimum value of ff on [0,27][0,27].

Create a free account to view solutions

Create a free account to view solutions

Recommended textbook solutions

Thomas' Calculus 14th Edition by Christopher E Heil, Joel R. Hass, Maurice D. Weir

Thomas' Calculus

14th EditionISBN: 9780134438986 (11 more)Christopher E Heil, Joel R. Hass, Maurice D. Weir
10,142 solutions
Calculus: Early Transcendentals 3rd Edition by Bernard Gillett, Eric Schulz, Lyle Cochran, William L. Briggs

Calculus: Early Transcendentals

3rd EditionISBN: 9780134763644 (5 more)Bernard Gillett, Eric Schulz, Lyle Cochran, William L. Briggs
13,437 solutions
Calculus: Early Transcendentals 8th Edition by James Stewart

Calculus: Early Transcendentals

8th EditionISBN: 9781285741550 (1 more)James Stewart
11,084 solutions
Calculus: Early Transcendentals 9th Edition by Daniel K. Clegg, James Stewart, Saleem Watson

Calculus: Early Transcendentals

9th EditionISBN: 9781337613927 (3 more)Daniel K. Clegg, James Stewart, Saleem Watson
11,048 solutions

More related questions

1/4

1/7