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3 years ago

37+(-7) its has sentaces not numbers

Mathematics

1 answer:

jok3333 [9.3K]3 years ago

3 0

Answer:

should be 30

Step-by-step explanation:

(-)+ makes - so 37-7

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X + y = 3

hoa [83]

Answer: x=2
step by step explanation:

6 0

3 years ago

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8) Use the slope formula to find the slope between<br> the points: (-1,2) and (3,- 3)<br> m =

nikdorinn [45]

Answer:

-5/4

Step-by-step explanation:

We can use the slope formula to find the slope

m = ( y2-y1)/(x2-x1)

= ( -3 -2)/( 3 - -1)

= ( -3-2 ) /( 3+1)

= -5/4

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3 years ago

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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.

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.

7 0

3 years ago

Identify the slope.Nadia's pool already has 1000 gallons of water when she begins to fill it. It fills at a rate of 22 gallons p

Nataly_w [17]

Y=22x+100
22 would be the slope

3 0

3 years ago

Given the diagram above . . .<br> 1. Is m∠A = 105? Explain.<br> 2. Is ∠B = 75? Explain.

maw [93]

1. Angle A is not 105degrees. As you can see on the horizontal line that it lies on, it's under 90degrees(acute). The angle aside from it is over 90degrees(obtuse).

2.Angle B is in fact not 75degrees.. By looking at the angle it's obtuse, over 90 degrees, so it can't be 75degrees.

6 0

3 years ago