5(2x-3) –3(x+4)/9?

You are situated 300 feet from the base of Tower Glitz Plaza watching an external elevator descend down the side of the building

nordsb [41]

Answer:

18.66 ft/s

Step-by-step explanation:

The distance between you and the elevator is given by:

$h=\sqrt{x^2+y^2}$

The rate of change for the distance between you and the elevator is given by:

$\frac{dh}{dt}=\frac{dh}{dy}*\frac{dy}{dt}$

$-16=\frac{dh}{dy}*\frac{dy}{dt}$

$\frac{dh}{dy}=\frac{d}{dy} (\sqrt{x^2+y^2})\\$

Applying the chain rule:

$u=x^2+y^2\\\frac{dh}{dy}=\frac{d\sqrt u}{du} *\frac{du}{dy}\\\frac{dh}{dy}=\frac{1}{2\sqrt u} *2y\\\frac{dh}{dy}=\frac{y}{\sqrt {(x^2+y^2)}}$

Therefore, at x=300 and y = 500, dy/dt is:

$-16=\frac{y}{\sqrt {(x^2+y^2)}}*\frac{dy}{dt}\\-16=\frac{500}{\sqrt {(300^2+500^2)}}*\frac{dy}{dt}\\\frac{dy}{dt}=-18.66\ ft/s$

The elevator is descending at 18.66 ft/s.

7 0

3 years ago

Please help! 30 points!

Rashid [163]

Answer: $64.2^{\circ}$

Step-by-step explanation:

According to the cosine rule

$\cos C=\dfrac{a^2+b^2-c^2}{2ab}$

Here, $a=83, b=111, c=165,\ C=180^{\circ}-\theta$

Putting values

$\Rightarrow \cos (180^{\circ}-\theta)=\dfrac{83^2+111^2-165^2}{2\times 83\times 111}\\\\\Rightarrow \cos(180^{\circ}-\theta)=\dfrac{6889+12321-27225}{18426}\\\\\Rightarrow \cos(180^{\circ}-\theta)=\dfrac{-8015}{18426}=-0.4349\\\\\Rightarrow 180^{\circ}-\theta=\cos^{-1}(-0.4349)=115.77^{\circ}\\\Rightarrow \theta=64.23\approx 64.2^{\circ}$

So, the ship turns by $64.2^{\circ}$ north of west

8 0

3 years ago

I need help ASAP

GaryK [48]

Answer:

500

Step-by-step explanation:

Define listed price = C

Based on the term, to have the balance on both plan, the equation is 30+90%C = 80+80%C

30+0.9C=80+0.8C
0.1C=50
1C = 500

6 0

2 years ago

Solve the inequality.-5 (x-1) > -40

Tresset [83]

Step-by-step explanation:

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5 0

3 years ago

A system of equations is given below:

My name is Ann [436]

Solving by substitution:

y = 4x - 3

2x + 7y = 41

Let us substitute the first equation y = 4x - 3 into the second.

2x + 7y = 41

2x + 7(y = 4x -3) = 41

2x + 7(4x -3) = 41

So that's the third option.

I hope this helps.

4 0

2 years ago

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