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vivado [14]
2 years ago
10

Between 0 degrees Celsius and 30 degrees Celsius, the volume V (in cubic centimeters) of 1 kg of water at a temperature T is giv

en approximately by the formula V=999.87−0.06426T+0.0085043T2−0.0000679T3 Find the temperature at which water has its maximum density. Temperature = degrees Celsius
Mathematics
1 answer:
Ira Lisetskai [31]2 years ago
3 0

Answer:

T = 3.967 C

Step-by-step explanation:

Density = mass / volume

Use the mass = 1kg and volume as the equation given V, we will come up with the following equation

D = 1 / 999.87−0.06426T+0.0085043T^2−0.0000679T^3

   = (999.87−0.06426T+0.0085043T^2−0.0000679T^3)^-1

Find the first derivative of D with respect to temperature T

dD/dT = \dfrac{70000000\left(291T^2-24298T+91800\right)}{\left(679T^3-85043T^2+642600T-9998700000\right)^2}

Let dD/dT = 0 to find the critical value we will get

\dfrac{70000000\left(291T^2-24298T+91800\right)}  = 0

Using formula of quadratic, we get the roots:

T =  79.53 and T = 3.967

Since the temperature is only between 0 and 30, pick T = 3.967

Find 2nd derivative to check whether the equation will have maximum value:

-\dfrac{140000000\left(395178T^4-65993368T^3+3286558821T^2+2886200857800T-121415215620000\right)}{\left(679T^3-85043T^2+642600T-9998700000\right)^3}

Substituting the value with T=3.967,

d2D/dT2 = -1.54 x 10^(-8)    a negative value. Hence It is a maximum value

Substitute T =3.967 into equation V, we get V = 0.001 i.e. the volume when the the density is the highest is at 0.001 m3 with density of

D = 1/0.001 = 1000 kg/m3

Therefore T = 3.967 C

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The equation r = 6t gives the number of albums released, r, by a record label over time in years, t. If you graph this relations
svp [43]
Choices:
(7, 44)
(8, 48)
(9, 52)
(12, 74)
<span>(13, 78)

r = 6t 
(7,44) : r = 6(7) = 42 incorrect 
(8,48) : r = 6(8) = 48 CORRECT
(9,52) : r = 6(9) = 54 incorrect
(12,74) : r = 6(12) = 72 incorrect
(13,78) : r = 6(13) = 78 CORRECT

The points that lie on the resulting line are (8,48) and (13,78)</span>
4 0
2 years ago
Read 2 more answers
Solve for x: three fourths times x plus five fourths equals four times x
denis-greek [22]

Answer:

The value of x for the given expression is \dfrac{5}{13}

Step-by-step explanation:

Given as :

The statement is , three fourths times x plus five fourths equals four times x

So, \dfrac{3}{4} × x + \dfrac{5}{4} = 4 × x

<u>Now, rearranging the equation</u>

i.e 4 x -  \dfrac{3}{4} × x = \dfrac{5}{4}

Or, 4 x -  \dfrac{3 x}{4}  = \dfrac{5}{4}

Or, \dfrac{16 x - 3 x}{4}  = \dfrac{5}{4}

Or, \dfrac{13 x}{4}  = \dfrac{5}{4}

Or, 13 x = \dfrac{5}{4} × 4

Or, 13 x = 5

∴ x = \dfrac{5}{13}

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5 0
1 year ago
What is the final amount if 784 is decreased by 1% followed by a 4% increase?
Iteru [2.4K]

Answer:

The final amount  if 784 is decreased by 1% followed by a 4% increase is 807.52.

Step-by-step explanation:

General Formula

<em>A way to solve this problem is as follows</em>:

The general formula for this is taking into account that:

\\ percent\;change = \frac{change}{starting\;point}

The <em>starting point</em> is number 784.

The most important key is the solution for this answer is that:

\\ change = starting\;point - x

Where <em>x</em> is a number that we need to find. Then

\\ percent\;change = \frac{starting\;point - x}{starting\;point} [1]

Is 784 increased or decreased after all?

We also need to evaluate the following: if a quantity decreases a percentage, and then increases in another percentage, what is the final percentage? In this case, we have first that 784 decreases by 1% and then increases by 4%. As a result 784 will +4% - 1% = +3%, that is, 784 will increase in 3%.

Finding the result

If 784 increases by 3%, we have:

\\ 3\% = \frac{784 - x}{784}

Which is equal to

\\ 0.03 = \frac{784 - x}{784}

Solving for <em>x</em>, we first multiply by 784 to both sides of the previous formula:

\\ 0.03 * 784 = \frac{784 - x}{784}*784

\\ 0.03 * 784 = (784 - x)*\frac{784}{784}

\\ 0.03 * 784 = (784 - x)*1

\\ 0.03 * 784 = (784 - x)

Remember that if we add, subtract, multiply, divide... to both sides of the equation, we do not "alter" this equation.

Subtracting 784 to both sides:

\\ (0.03 * 784) - 784 = (784 - 784 - x)

\\ (0.03 * 784) - 784 = (0 - x)

\\ (0.03 * 784) - 784 = - x

\\ 23.52 - 784 = - x

\\ -760.48 = - x

Multiplying by -1 to both sides:

\\ -1 * (-760.48) = -1 * (-x)

We have to remember that:

\\ +*+ = +; - * - = +; - * + = -; + * - = -

\\ 760.48 = x

Then

\\ x = 760.48

Therefore, using formula [1], an increase of 3% is

\\ 3\% = \frac{784 - 760.48}{784}

\\ change = 784 - 760.48

\\ change = 23.52

Since an increase of 3% is 23.52, we have to add this to the starting point 784, and finally the amount is 784 + 23.52 = 807.52.

As a result, the final amount if 784 is decreased by 1% followed by a 4% increase is 807.52.  

In a more <em>terse way</em> of solving this problem, we can say that:

Increase of 4% = 784 * 0.04 = 31.36.

Decrease of 1% = 784 * 0.01 = 7.84.

Difference = 31.36 - 7.84 = 23.52.

Then, we need to add this value to 784, and 784 + 23.52 = 807.52 (the same result).

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1 year ago
Anyone know the answer??
olga_2 [115]
No. no i do not so yeah.
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Irina18 [472]
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2 years ago
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