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Semenov [28]
3 years ago
6

PLEASE HELP WITH THIS ONE QUESTION

Mathematics
1 answer:
Mnenie [13.5K]3 years ago
4 0

Answer:

  (a)  7/x = 3x/21

Step-by-step explanation:

The proportion that shows the ratio of solution to water in each case is ...

  7/x = 3x/21 . . . . matches the first choice

__

The other equations are wrong on their face. They all simplify to 3 = 1/3, which is false.

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Re-Write<br><br> 51/40<br> as a decimal.
kati45 [8]

Answer:

1.275

Step-by-step explanation:

4 0
2 years ago
Read 2 more answers
X + y = 8<br> 3x - y = 12
Virty [35]

Answer:

x = 5 and y = 3

Step-by-step explanation

y crosses out so you are left with

4x = 20 (divide by 4)

x = 5

plug x into either equation

5 + y = 8 (subtract 5)

y = 3

7 0
3 years ago
Litter such as leaves falls to the forest floor, where the action of insects and bacteria initiates the decay process. Let A be
Travka [436]

Answer:

D = L/k

Step-by-step explanation:

Since A represents the amount of litter present in grams per square meter as a function of time in years, the net rate of litter present is

dA/dt = in flow - out flow

Since litter falls at a constant rate of L  grams per square meter per year, in flow = L

Since litter decays at a constant proportional rate of k per year, the total amount of litter decay per square meter per year is A × k = Ak = out flow

So,

dA/dt = in flow - out flow

dA/dt = L - Ak

Separating the variables, we have

dA/(L - Ak) = dt

Integrating, we have

∫-kdA/-k(L - Ak) = ∫dt

1/k∫-kdA/(L - Ak) = ∫dt

1/k㏑(L - Ak) = t + C

㏑(L - Ak) = kt + kC

㏑(L - Ak) = kt + C'      (C' = kC)

taking exponents of both sides, we have

L - Ak = e^{kt + C'} \\L - Ak = e^{kt}e^{C'}\\L - Ak = C"e^{kt}      (C" = e^{C'} )\\Ak = L - C"e^{kt}\\A = \frac{L}{k}  - \frac{C"}{k} e^{kt}

When t = 0, A(0) = 0 (since the forest floor is initially clear)

A = \frac{L}{k}  - \frac{C"}{k} e^{kt}\\0 = \frac{L}{k}  - \frac{C"}{k} e^{k0}\\0 = \frac{L}{k}  - \frac{C"}{k} e^{0}\\\frac{L}{k}  = \frac{C"}{k} \\C" = L

A = \frac{L}{k}  - \frac{L}{k} e^{kt}

So, D = R - A =

D = \frac{L}{k} - \frac{L}{k}  - \frac{L}{k} e^{kt}\\D = \frac{L}{k} e^{kt}

when t = 0(at initial time), the initial value of D =

D = \frac{L}{k} e^{kt}\\D = \frac{L}{k} e^{k0}\\D = \frac{L}{k} e^{0}\\D = \frac{L}{k}

4 0
3 years ago
Simplify. if q = 8, evaluate -q
trasher [3.6K]
<h2>Answer:</h2>

<em>Then the -q would be </em><em>-8.</em><em> </em>

It is because there is negative sign before the variable.

<em>I hope I helped you. I will be really happy, If you mark my answer as the brainliest.Your David.</em>


8 0
3 years ago
Read 2 more answers
Can you relly much help me do this
slava [35]
Hey!
So It would be set up as .75n -2 = 10
.75 is the same as 3/4
Now add 2 to both sides
.75n = 12
now we want to get n alone so that we know what the number is, so divide .75 to both sides since it's multiplied to n
n=16
The answer is D!
Hope this helps!
5 0
3 years ago
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