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3 years ago

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I need help. on math

1 answer:

andreev551 [17]3 years ago

5 0

Answer:

Use a calculator.

Step-by-step explanation:

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5. A tank initially contains 20 lb of salt dissolved in 200-gallon of water. Starting at time t = 0, a solution containing 0.5 l

sladkih [1.3K]

Answer:

(a) Amount of salt as a function of time

$A(t)=100-80e^{-0.02t}$

(b) The time at which the amount of salt in the tank reaches 50 lb is 23.5 minutes.

(c) The amount of salt when t approaches to +inf is 100 lb.

Step-by-step explanation:

The rate of change of the amount of salt can be written as

$\frac{dA}{dt} =rate\,in\,-\,rate\,out\\\\\frac{dA}{dt}=C_i*q_i-C_o*q_o=C_i*q_i-\frac{A(t)}{V}*q_o\\\\\frac{dA}{dt}=0.5*4-\frac{A(t)}{200}*4\\\\\frac{dA}{dt} =\frac{100-A(t)}{50}=-(\frac{A(t)-100}{50})$

Then we can rearrange and integrate

$\frac{dA}{dt}= -(\frac{A(t)-100}{50})\\\\\int \frac{dA}{A-100}=-\frac{1}{50} \int dt\\\\ln(A-100)=-\frac{t}{50}+C_0\\\\ A-100=Ce^{-0.02*t}\\\\\\A(0)=20 \rightarrow 20-100=Ce^0=C\\C=-80\\\\A=100-80e^{-0.02t}$

Then we have the model of A(t) like

$A(t)=100-80e^{-0.02t}$

(b) The time at which the amount of salt reaches 50 lb is

$A(t)=100-80e^{-0.02t}=50\\\\e^{-0.02t}=(50-100)/(-80)=0.625\\\\-0.02*t=ln(0.625)=-0.47\\\\t=(-0.47)/(-0.02)=23.5$

(c) When t approaches to +infinit, the term e^(-0.02t) approaches to zero, so the amount of salt in the solution approaches to 100 lb.

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3 years ago

The table shows the weight of a dog in pounds at various ages in months. Age vs. Weight of a Dog Age in months Weight in pounds

Ainat [17]

Answer:

A

Step-by-step explanation:

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3 years ago

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3m ≤ –9 solve the inequality

erica [24]

ANSWER: The inequality form is: m <u><</u> -3

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2 years ago

Do these form a proportion? please help me!!!

mel-nik [20]

Answer:

yes they do

Step-by-step explanation:

both equal 1/3

8/24 = 1/3

5/15 = 1/3

1/3 = 1/3

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3 years ago

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Which step comes first -b-2<8

Bingel [31]

Answer:

Step-by-step explanation:

Alright so the step that comes first is adding two to both sides.

Let me show you,

Step 1

-b-2<8 Add 2 to both sides

-b<10

Then you divide the sides by -1

-b<10

b>-10

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3 years ago