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3 years ago

Offering 25 pts and a mark for real answers please!!! Flying against the jetstream, a jet travels

Mathematics

1 answer:

almond37 [142]3 years ago

4 0

Answer:

plane: 850 mph
jet stream: 150 mph

Step-by-step explanation:

The speed of the plane is the average of the two speeds. The speed of the jet stream is half their difference.

against: (5600 mi)/(8 h) = 700 mi/h

with: (4000 mi)/(4 h) = 1000 mi/h

Plane's speed = (700 + 1000)/2 mi/h = 850 mi/h

jetstream speed = (1000 -700)/2 mi/h = 150 mi/h

The rate of the jet in still air is 850 mi/h; the rate of the jetstream is 150 mi/h.

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The temperature, H, in degrees Celsius, of a cup of coffee placed on the kitchen counter is given by H = f(t), where t is in min

Deffense [45]

Answer:

f'(t) is negative

The unit is degC/min

At 35 minutes after the coffee was put on the counter, its temperature is 68 and will decrease by about 0.75 in the next 30 seconds.

Step-by-step explanation:

From the question we are told we are told that

The equation for the temperature of a cup of coffee place on a counter is

$H= f(t)$

Here t is the time in minutes the coffee was put on the counter

Generally f(t)' is the derivative of f(t) at it represents the change of the temperature of the cup of coffee with respect to time

Generally for the coffee placed on the counter after a couple of minutes the temperature will decrease hence f(t)' is negative

Generally the unit of the temperature is in degrees Celsius while that of time is in minutes

So the change in temperature with time f(35)' will be in degrees Celsius/minutes (i.e degC/min)

From the question we are told that

$|f(35)'| = 1.5$

i.e the rate of change of temperature after 35 minutes is 1.5

and

$|f(35)| = 68$

i.e the temperature of the cup of coffee after 35 minutes is 67 degC

Now after another t= 30 seconds = $\frac{30}{60}= 0.5 \ minutes$ the rate of change of the temperature of the cup of coffee is

$R = |f(35)'| * t$

=> $R = 1.5 * 0.5$

=> $R = 0.75$

At 35 minutes after the coffee was put on the counter, its temperature is 68 and will decrease by about 0.75 in the next 30 seconds.

5 0

3 years ago

Find the value of k if (x-3) is a factor of P(x)=2x3-5x2+3x+k

blsea [12.9K]

Answer:

k = -18

Step-by-step explanation:

If x-3 is a factor, what this means is that if we substitute;

x = 3 into the equation, we should get 0

This is from the factor theorem

Thus ;

P(3) = 0 = 2(3)^3 -5(3)^2 + 3(3) + k

0 = 54 - 45 + 9 + k

k + 18 = 0

k = -18

4 0

3 years ago

1/2(n-5)=1/2(23-5) I cannot find what’s half of 23-5

liraira [26]

Answer:

n = 23

Step-by-step explanation:

if 1/2 (n-5) = 1/2 (23-5)

that must mean that n=23.

and if you are just looking for 1/2 of 23-5 that is just 9. (23-5) = 18 and half of 18 is 9

3 0

2 years ago

How many solutions does the following equation have?

IrinaK [193]

Answer:
Exactly one solution

Explanation:
The first step we need to take to find the answer is to find the value of y.

7(y+3)=5y+8
Expand the parentheses
7y+21=5y+8
Subtract both sides by 21
7y+21-21=5y+8-21
7y=5y-13
Subtract both sides by 5y
7y-5y=5y-13-5y
2y=-13
Divide both sides by 2
2y/2=-13/2
y=-6.5

Now, we plug y back into the original equation.

7(y+3)=5y+8
7(-6.5+3)=5(-6.5)+8
Expand the parentheses
-45.5+21=-32.5+8
-24.5=-24.5

Because both sides of the equation is equal and the equation is true, we can conclude that the equation has one solution.

I hope this helps!

7 0

3 years ago

32%

lisabon 2012 [21]

At least 4

10% of 12 is 1.2

So 30% is 3.6

And 1% 0.12

So 2% is 0.24

Plus 3.6 onto 0.24 and you get 3.84

4 0

3 years ago