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3 years ago

Can someone help me please..

Mathematics

1 answer:

Elza [17]3 years ago

5 0

So just find circumference is
circumfernce=2pir or pid
so diameter 2.5 ft
just for this problem aprox pi=3.14 so
c=pid
c=3.14(2.5)
c=7.85

a. 7.85 ft

b. how many times revolution till one mile (5280)
so
7.85 times x revolutions=5280
divide both sides b y7.85
x revolutions=672.61
round up so we complete the mile (about how many times..)
673 is the answer

a. 7.85 ft
b. 673 times

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I have given it step by step below.

Step-by-step explanation:

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3 years ago

If the price is increasing at a rate of 2 dollars per month when the price is 10 dollars, find the rate of change of the demand.

densk [106]

Answer:

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Step-by-step explanation:

Given

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Required

Determine the rate of change of demand

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$2x^2+5xp+50p^2=24800.$

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Collect like terms

$4x\frac{dx}{dt} + 5p\frac{dx}{dt} = -5x\frac{dp}{dt} - 100p\frac{dp}{dt}$

Factorize

$\frac{dx}{dt}(4x + 5p) = -5(x + 20p)\frac{dp}{dt}$

Solve for dx/dt

$\frac{dx}{dt} = -\frac{5(x + 20p)}{4x + 5p}\cdot \frac{dp}{dt}$

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Solve for x

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Equate to 0

$2x^2 + 50x + 5000 - 24800 =0$

$2x^2 + 50x -19800 =0$

Using a quadratic calculator, we have:

$x \approx -113\ and\ x\approx88$

Demand must be greater than 0;

So: $x=88$

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The rate of change of demand is:

$\frac{dx}{dt} = -\frac{5(88 + 20*10)}{4*88 + 5*10} * 2$

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