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Schach [20]
3 years ago
5

Solve for u. 8u-21 = 2u-9

Mathematics
2 answers:
erastovalidia [21]3 years ago
6 0

Answer:

u=2

Step-by-step explanation:

8u-21 = 2u-9

+21             +21

8u= 2u + 12

-2u    -2u

6u= 12

divide by 6, u=2 !!

garri49 [273]3 years ago
3 0

Answer:

u = 2

Step-by-step explanation:

8u - 21 = 2u - 9

subtract 2 u from both sides

6u - 21 = -9

add 21 to both sides

6u = 12

divide both sides by 6

u = 2

hope this helps

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Demand for Tablet Computers The quantity demanded per month, x, of a certain make of tablet computer is related to the average u
soldier1979 [14.2K]

x = f ( p ) = \frac { 100 } { 9 } \sqrt { 810,000 - p ^ { 2 } } } \\\\ \qquad { p ( t ) = \dfrac { 400 } { 1 + \dfrac { 1 } { 8 } \sqrt { t } } + 200 \quad ( 0 \leq t \leq 60 ) }

Answer:

12.0 tablet computers/month

Step-by-step explanation:

The average price of the tablet 25 months from now will be:

p ( 25) = \dfrac { 400 } { 1 + \dfrac { 1 } { 8 } \sqrt { 25 } } + 200 \\= \dfrac { 400 } { 1 + \dfrac { 1 } { 8 } \times 5 } + 200\\\\=\dfrac { 400 } { 1 + \dfrac { 5 } { 8 } } + 200\\p(25)=\dfrac { 5800 } {13}

Next, we determine the rate at which the quantity demanded changes with respect to time.

Using Chain Rule (and a calculator)

\dfrac{dx}{dt}= \dfrac{dx}{dp}\dfrac{dp}{dt}

\dfrac{dx}{dp}= \dfrac{d}{dp}\left[{ \dfrac { 100 } { 9 } \sqrt { 810,000 - p ^ { 2 } } }\right] =-\dfrac{100}{9}p(810,000-p^2)^{-1/2}

\dfrac{dp}{dt}=\dfrac{d}{dt}\left[\dfrac { 400 } { 1 + \dfrac { 1 } { 8 } \sqrt { t } } + 200 \right]=-25\left[1 + \dfrac { 1 } { 8 } \sqrt { t } \right]^{-2}t^{-1/2}

Therefore:

\dfrac{dx}{dt}= \left[-\dfrac{100}{9}p(810,000-p^2)^{-1/2}\right]\left[-25\left[1 + \dfrac { 1 } { 8 } \sqrt { t } \right]^{-2}t^{-1/2}\right]

Recall that at t=25, p(25)=\dfrac { 5800 } {13} \approx 446.15

Therefore:

\dfrac{dx}{dt}(25)= \left[-\dfrac{100}{9}\times 446.15(810,000-446.15^2)^{-1/2}\right]\left[-25\left[1 + \dfrac { 1 } { 8 } \sqrt {25} \right]^{-2}25^{-1/2}\right]\\=12.009

The quantity demanded per month of the tablet computers will be changing at a rate of 12 tablet computers/month correct to 1 decimal place.

8 0
2 years ago
Abdi has two electric train sets: A and B. Each train is on its own circular track. He starts both trains at the same time. Trai
mrs_skeptik [129]

Answer: 36 seconds

Step-by-step explanation:

A: 9, 18, 27, 36

B: 12, 24, 36

3 0
3 years ago
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Answer:

This number is 5008405

Step-by-step explanation:

five million = 5000000

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2 years ago
How do i factor s^2+9s=-20
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To factor you have to do this: 

s^2 + 9s = -20
      + 20    +20

s^2 + 9s + 20 = 0

now you need to numbers that multiplied give you 20 
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5+ 4 = 9

(x + 4) (x+ 5)

that means that x= -4, and -5
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I think it's 5, I made a paper airplane and counted.
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