What is 108 minus 36 explain please

A street light is at the top of a 25 ft pole. A 4 ft tall girl walks along a straight path away from the pole with a speed of 6

Burka [1]

Answer:

Tip of the shadow of the girl is moving with a rate of 7.14 feet per sec.

Step-by-step explanation:

Given : In the figure attached, Length of girl EC = 4 ft

Length of street light AB = 25 ft

Girl is moving away from the light with a speed = 6 ft per sec.

To Find : Rate ( $\frac{dw}{dt}$ ) of the tip (D) of the girl's shadow (BD) moving away from th

light.

Solution : Let the distance of the girl from the street light is = x feet

Length of the shadow CD is = y feet

Therefore, $\frac{dx}{dt}=6$ feet per sec. [Given]

In the figure attached, ΔAFE and ΔADE are similar.

By the property of similar triangles,

$\frac{x}{21}=\frac{x+y}{25}$

25x = 21(x + y)

25x = 21x + 21y

25x - 21x = 21y

4x = 21y

y = $\frac{4x}{21}$

Now we take the derivative on both the sides,

$\frac{dy}{dt}=\frac{4}{21}\times \frac{dx}{dt}$

= $\frac{4}{21}\times 6$

= $\frac{8}{7}$

≈ 1.14 ft per sec.

Since w = x + y

Therefore, $\frac{dw}{dt}= \frac{dx}{dt}+\frac{dy}{dt}$

$\frac{dw}{dt}=6+1.14$

= 7.14 ft per sec.

Therefore, tip of the shadow of the girl is moving with a rate of 7.14 feet per sec.

3 0

3 years ago

Solve for k 5/8(3k+1)-1/4(7k+2)=1

lesya [120]

Answer:

Step-by-step explanation:

$\dfrac{5}{8}(3k+1)-\dfrac{1}{4}(7k+2)=1\qquad\text{multiply both sides by 8}\\\\8\!\!\!\!\diagup^1\cdot\dfrac{5}{8\!\!\!\!\diagup_1}(3k+1)-8\!\!\!\!\diagup^2\cdot\dfrac{1}{4\!\!\!\!\diagup_1}(7k+2)=8\cdot1\\\\5(3k+1)-2(7k+2)=8\qquad\text{use the distributive property}\ a(b+c)=ab+ac\\\\(5)(3k)+(5)(1)+(-2)(7k)+(-2)(2)=8\\\\15k+5-14k-4=8\qquad\text{combine like terms}\\\\(15k-14k)+(5-4)=8\\\\k+1=8\qquad\text{subtract 1 from both sides}\\\\k=7$

3 0

3 years ago

What's the numerator for the following rational<br> expression?<br> X/y + 3/y= ?/y

Fittoniya [83]

Answer:

x + 3

Step-by-step explanation:

Since we have a common denominator, we can just simply combine the numerator which is just x+3.

7 0

3 years ago

Courtney would like to buy a new ca in 4 years. It is estimated that a new car will cost her 25,000 and that she will get 13,000

KiRa [710]

4 years=48 months

A new car costs 25,000, but she will get 13,000 for her used car as long as she takes good car of it. If she takes good care of her used car and gets 13,000 for it, she will only need to save 12,000 total. We can divide 12,000 by 48 to find out how much Courtney should save minimum each month to afford her new car. 12,000/48=250

You can check to see if this is correct by multiplying 48*250=12,000. Paying 250 for each month of the 48 months will equal the $12,000 that Courtney needs.

Courtney needs to save at least $250 per month to afford her new car in 4 years.

I hope this helps :)

3 0

3 years ago

It also detects if you are right or wrong

kap26 [50]

Answer:

50

Step-by-step explanation:

all your doing is dividing 100 by 20 and u get 50

6 0

3 years ago

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