Help me please I'm on a time limit

Find the absolute maximum and absolute minimum values of f on the given interval. f(t) = 2 cos(t) + sin(2t),[0, π/2].

castortr0y [4]

Answer:

The absolute maximum is $\frac{3\sqrt 3}2$ and the absolute minimum value is $0.$

Step-by-step explanation:

Differentiate of $f$ both sides w.r.t. $t$ ,

$f(t)=2 \cos t+\sin 2t$

$\Rightarrow f'(t)=-2\sin t+2\cos 2t$

Now take $f'(t)=0$

$\Rightarrow -2\sin t+2\cos 2t=0$

$\Rightarrow 2\cos 2t=2\sin t$

$\Rightarrow \cos 2t=\sin t$

$\Rightarrow 1-2\sin ^2t =\sin t \quad \quad [\because \cos 2t = 1-2\sin ^2t]$

$\Rightarrow 2\sin ^2t+\sin t-1=0$

$\Rightarrow 2\sin ^2t+2\sin t-\sin t-1=0$

$\Rightarrow 2\sin t(\sin t+1)-1(\sin t+1)=0$

$\Rightarrow (\sin t+1)(2\sin t-1)=0$

$\Rightarrow \sin t+1=0 \;\text{and}\; 2\sin t-1=0$

$\Rightarrow \sin t =-1 \;\text{and}\; \sin t =\frac 12$

In the interval $0\leq t\leq \frac {\pi}2$ , the answer to this problem is $\frac {\pi}6$

Now find the second derivative of $f(t)$ w.r.t. $t$ ,

$f''(t)=-2\cos t-4\sin 2t$

$\Rightarrow \left[f''(t)\right]_{t=\frac {\pi}6}=-2\times \frac {\sqrt 3}2-4\times \frac{\sqrt 3}2=-3\sqrt 3$

Thus, $f(t)$ is maximum at $t=\frac {\pi}6$ and minimum at $t=0$

$\left[f(t)\right]_{t=\frac {\pi}6}=2\times \frac {\sqrt 3}2+\frac{\sqrt 3}2=\frac{3\sqrt 3}2\;\text{and}\;\left[f(t)\right]_{t=\frac{\pi}2}= 2\times 0+0=0$

Hence, the absolute maximum is $\frac{3\sqrt 3}2$ and the absolute minimum value is $0$ .

7 0

3 years ago

How to solve 3x^2-72 = 0 using square root property?

erik [133]

3x^2 - 72 = 0
3x^2 = 72
x^2 = 24
x = squareroot(24)
x = 4.9

5 0

3 years ago

HELP!! 5) Which number is IRRATIONAL? A) V9 B) V27 C) V36 D) V81

kozerog [31]

I think it’s B) V27 i could me wrong

7 0

3 years ago

It takes 313131 employees and \$7500$7500dollar sign, 7500 to build a car, and it takes 191919 employees and \$4300$4300dollar s

Rainbow [258]

Complete question :

It takes 313131 employees and \$7500$7500dollar sign, 7500 to build a car, and it takes 191919 employees and \$4300$4300dollar sign, 4300 to build a motorcycle. Genghis Motors wants to spend more than \$84000$84000dollar sign, 84000 to build cars and motorbikes using at most 706706706 employees. Let CCC denote the number of cars they build and MMM the number of motorbikes they build. Write an inequality that represents the condition based on the number of employees. Write an inequality that represents the condition based on the number of dollars.

Answer:

31C + 19M ≤ 706

7500C + 4300M > 84000

Step-by-step explanation:

C = number of cars built

M = number of motorcycles built

Cost of building a car :

Cost = 31 + $7500

Cost of building a motorcycle,:

Cost = 19 + 4300

To build, C cars :

Number of employees = 31C

7500 * C = 7500C

To build, M motorcycles :

Number of employees = 19M

4300 * M = 4300M

Genghis budget :

Amount > 84000

Number of employees ≤ 706

Hence, the constraints

31C + 19M ≤ 706

7500C + 4300M > 84000

5 0

3 years ago

A sixth-grade class must raise at least $447 to go on a field trip. The amount of money, m, that each of the 30 students must ra

Virty [35]

Answer:

Each student must raise $14.90

Step-by-step explanation:

This is actually fairly easy to figure out (at least this part) all you do is 447/30 and then you get your 14.9 (14.90)

m = 14.90

30m = 447

4 0

3 years ago