Answer:
[tex]dA(t)/dt = -\frac{3}{7}e^{-t/70}[/tex] g/min
Step-by-step explanation:
The mass flow rate dA(t)/dt = mass flowing in - mass flowing out
Since water is pumped in at a rate of 3 L/min, and it contains no salt, the concentration in is thus 0 g/L. the mass flow in is thus 0 g/L × 3 L/min = 0 g/min.
Let A(t) be the mass present at any time, t. The concentration at any time ,t is thus A(t)/volume = A(t)/210. Since water flows out at a rate of 3 L/min, the mass flow out is thus, A(t)/210 g/L × 3 L/min = A(t)/70 g/min.
So, dA(t)/dt = mass flowing in - mass flowing out
dA(t)/dt = 0 g/min - A(t)/70 g/min
dA(t)/dt = - A(t)/70 g/min
Since the tank initially contains 30 g of salt, the initial mass of salt in the tank is 30 g. So A(0) = 30
So, the initial value problem is thus
dA(t)/dt = - A(t)/70 , A(0) = 30
Separating the variables, we have
dA(t)/A(t) = -dt/70
Integrating both sides, we have
∫dA(t)/A(t) = ∫-dt/70
㏑A(t) = -t/70 + C
taking exponents of both sides, we have
A(t) = exp(-t/70 + C)
A(t) = exp(-t/70)expC
[tex]A(t) = e^{-t/70}e^{C}\\A(t) = Ce^{-t/70} whereC = e^{C}[/tex]
A(0) = 30, So
[tex]A(0) = Ce^{-0/70}\\30 = Ce^{0}\\C = 30[/tex]
[tex]A(t) = 30e^{-t/70}[/tex]
The rate at which the number of grams of salt in the tank is changing at time t is
[tex]dA(t)/dt = \frac{d30e^{-t/70} }{dt} \\dA(t)/dt = -\frac{30e^{-t/70} }{70}\\dA(t)/dt = -\frac{3}{7}e^{-t/70}[/tex]
So, the rate at which the number of grams of salt in the tank is changing at time t is
[tex]dA(t)/dt = -\frac{3}{7}e^{-t/70}[/tex] g/min
Find the highest common factor (HCF) of 90 and 126
Answer:
18
Step-by-step explanation:
18*5=90
18*7=126
A new parking lot is being built for a medical office. The expression representing the number of parking spots in the new lot is StartFraction 15 x over 4 EndFraction minus 9, where x represents the number of parking spots in the first row. How many spots are in the parking lot if there are 32 parking spots in the first row?
79
88
111
129
Answer:
111
Step-by-step explanation:
A variable is a letter, for example x, y or z, that represents an unspecified number. To evaluate an algebraic expression, you have to substitute a number for each variable and perform the arithmetic operations. In the example above, the variable x is equal to 6 since 6 + 6 = 12.
Answer:
C
Step-by-step explanation:
Find the coordinates of the center and the measure of the radius for a circle whose equation is (x - 3)^2 + (y - 7)^2 = 2.
A. center = (3,7), radius = √2
B. center = (3,7), radius = 1
C. center = (-3, -7), radius =4
D. center = (-3, -7), radius =1
Answer:
A
Step-by-step explanation:
Equation for a circle of radius r, centered at (h,k):
(x-h)² + (y-k)² = r²
The coordinates of the center and the measure of the radius for a circle given are center = (3,7), radius = √2.
What is a circle?A circle is a shape or a curve in a plane that has a fixed distance, called the radius, from a given point, called the center. A circle is also the set of all points that are equidistant from the center.
Given is an equation of a circle, we need to find coordinates of the center and the measure of the radius for a circle,
The equation of the circle =
(x - 3)² + (y - 7)² = 2
The standard equation for a circle of radius r, centered at (h,k):
(x-h)² + (y-k)² = r²
Comparing both we get,
(h, k) = (3, 7)
r² = 2
r = √2
Hence, the coordinates of the center and the measure of the radius for a circle given are center = (3,7), radius = √2.
Learn more about circle, click;
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PLEASE HELP ME I NEED THE ANSWER FAST.
Answer:
126
Step-by-step explanation:
9 by 10 is 90
9 by 4 is 36
90+36= 126
Hope this helps <3
200 students attend Ridgewood Junior High School. 25% of students bring their lunch to school everyday. How many students brought their lunch to school on Thursday?
sorry est un site Web Internet spécialement conçue 4
1. The temperature on a winter night in Kansas is - 6 Celsius. The
temperature decreases by 8 Celsius. What is the new temperature, in
degrees Celsius? *
In 2008, there were 1570 bears in a wildlife refuge. In 2010, the population had
increased to approximately 1884 bears. If this trend continues and the bear population is
increasing exponentially, find the number of bears in 2015?
Answer:
it would be about 4500 bears
Step-by-step explanation:
Lia cut a long piece of into 2 pieces. One pieces of the string is 24 inches long, and the other piece of the string is 12 inches long. How many feet long was the piece of string before lia cut it?
Answer:
24+12=36you find the total length
Answer:
3 feet
Step-by-step explanation:
Use the net to determine the total surface area. 10 cm 8 cm 8 cm 10 cm 8 cm 20 cm
440 cm2
880 cm2
144 cm2
72 cm2
Which graph represents-5x+4y≥-1?
Answer:
D!
Step-by-step explanation:
Desmos has a free graphing calculator for future references :)
how many 8ths are in a pound
Answer:There are 129 eighths in one pound of
Step-by-step explanation:
Select the true statement about triangle ABC.
A. sin A = sin C
B. sin A = cos B
C. sin A = cos C
D. sin A = tan c
Factorise
1) 9a^2 - 6a
Answer:
9a^2 - 6a
taking common
3a(3a-2)
Help
Select all that apply
Answer:
A, D
Step-by-step explanation:
It's basic math, height times length = Area.
Answer:
A and D are the only ones that i can see that would be correct
Step-by-step explanation:
Please explain in words.
Answer:
Negative
Step-by-step explanation:
The following expression will be negative. This is because, the fraction in x is a negative fraction. The fraction in y is a positive fraction. The expression is x * y, so if you were to multiply the two it would be negative. This is because a negative multiplied by a positive will be equal to a negative.
Hope this helps!!
-Ketifa
(Can I get brainliest?)
Please help!
Given the figure is a square, find x, y and z
Answer:
Step-by-step explanation:
Did u find it? Because I can’t figure it out euther
3/5x2/3 thanks for the help
3 x 2 6
-- -- = --
5 3 15
6/15 can be simplified to 2/5.
---
hope it helps
For a rhombus, which of the following statements are true? (select all that apply)
1)Opposite sides are parallel
2)All sides are congruent
3)Consecutive angles are congruent
4)Consecutive angles are supplementary
5)All angles are congruent
6)Opposite angles are congruent
Answer: 1,4,6
Step-by-step explanation:
https://quizlet.com/483245104/geometry-parallelogram-quiz-flash-cards/
I will gicve you 80 points if answered correctly
Answer:
3. A = (0,-3)
B = (4,-2)
C = (-1,1)
4. A = (0,-6)
B = (4,-5)
C = (-1,-2)
Step-by-step explanation:
3) Reverse coordinates (-3,0), (-2,4), (1,-1) to A=(0,-3), B=(4,-2), C=(-1,1).
4) These coordinates (0,-3), (4,-2), (-1,1) need to be moved 3 units down.
So number four answer is A=(0,-6), B=(4,-5), C=(-1,-2).
I hope this helped you.
f(x)= 3x+10 and g(x)= 3x-7
Answer:
1. x=-10/3
2. x=7/3
Step-by-step explanation:
plsssssssss mark me brainliest I need one more
Combine like terms
x + 10x-30= -8
Answer: x=2
Isolate the variable by dividing each side by the factors that don't contain variables.
Find the perimeter of quadrilateral ABCD. Round to the nearest tenth.
The perimeter of qudrilateral ABCD, to the nearest tenth is: 14.6 units.
What is the Perimeter of a Quadrilateral?Perimeter of a quadrilateral = sum of all its four sides.
Given the qudrilateral with the vertices:
A (3, 5)B (1, 3)C (3, -1)D (5, 3)Use the distance formula, [tex]d = \sqrt{(y_2 - y_1)^2 + (x_2 - x_1)^2}[/tex] to find AB, BC, CD, and AD.
AB = √[(1−3)² + (3−5)²]
AB = √8 = 2.8 units
BC = √[(1−3)² + (3−(−1))²
BC = √20 = 4.5 units
CD = √20 = 4.5 units
AB = √8 = 2.8 units
Perimeter of qudrilateral ABCD = 2.8 + 4.5 + 4.5 + 2.8 = 14.6 units.
Learn more about the perimeter of a quadrilateral on:
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Precalculus (view picture) pt2
Answer:
E
Step-by-step explanation:
A model rocket is launched directly upward at a speed of 20 meters per second from the ground. The function f(t)=−4.9t2+20t, models the relationship between the height of the rocket and the time after launch, t, in seconds. When, in seconds after launch, will the rocket reach its highest point? Round to two decimal places.
Answer:
The rocket will reach its highest point about 2.04 seconds.
Step-by-step explanation:
The function:
[tex]f(t)=-4.9t^2+20t[/tex]
Models the relationship between the height of the rocket and the time after launch t in seconds.
Since this is a quadratic function, the rocket will reach its highest point at its vertex. The vertex of a quadratic is given by:
[tex]\displaystyle \Big(-\frac{b}{2a}, f\Big(-\frac{b}{2a}\Big)\Big)[/tex]
In this case, a = -4.9, b = 20, and c = 0. Thus:
[tex]\displaystyle t=\frac{-(20)}{2(-4.9)}=\frac{10}{4.9}\approx 2.04[/tex]
The rocket reaches its maximum height after 10/4.9 or about 2.04 seconds.
Further Notes:
Then the maximum height of the rocket will be f(10/4.9):
[tex]\displaystyle f\Big(\frac{10}{4.9}\Big)=-4.9\Big(\frac{10}{4.9}\Big)^2+20\Big(\frac{10}{4.9}\Big)\approx20.41\text{ feet}[/tex]
What is -3/4x + 1/2y - 9/4x - 11/2y in simplest form?
Answer: -3x-5y
Step-by-step explanation:
Determine the equivalent system for the given system of equations.
4x − 5y = 2
10x − 21y = 10
A. 4x − 5y = 2
3x − y = 4
B. 4x − 5y = 2
24x − 47y = 22
C. 4x − 5y = 2
10x + 3y = 15
D. 4x − 5y = 2
14x + 26y = 12
Answer:
B) 4x − 5y = 2
24x − 47y = 22
if the function f(x)=2x-3 and g(x)= 3/2x + 1 which is a tru statement?
1- f(0)>g(0)
2- f(2)=g (2)
3- f(8)=g(8)
4- g(4)<f(4)
Answer: 3 f(8)=g(8)
Step-by-step explanation:
2(8)-3=3/2(8)+1
16-3=12+1
13=13
Answer:
3 is true
Step-by-step explanation:
f(x) =2x - 3→ 2*8 - 3 =13
g(x) = 3/2x + 1 → 3/2(8) + 1 = 3*4 +1 = 14
The table below gives a record of variations of the values of y with the values of x. Draw a scatter plot for the data.
Answer:
can you please show the table as it is not here
The Booster Club sells meals at basketball games . Each meal comes with a choice of a main: hamburgers , pizza , hot dogs, cheeseburgers , or tacos, and a choice of a drink: root beer, lemonade, milk, coffee, tea, or cola. How many possible sandwich/drink combinations are there? (Show work) (2 pts)
30 combinations is the answer.
Step-by-step explanation:
Each meal comes with a choice of hamburgers, pizza, hot dogs , cheeseburgers or tacos means 5 options.
And a choice of root beer lemonade, milk , coffee, tea or cola means 6 options.
So, possible combination can be = combinations.
please help i'm really stuck
Answer:
The scale factor is 1 : 3, and the missing length is 8
Step-by-step explanation:
The scale factor: 7/21 = 1/3, 6/18 = 1/3
The missing length: 24/3 = 8 or 8/24= 1/3
If it is right can you please give me a brainliest. Pls. It is fine if you didn't bu here's the answer
Answer:
so that will be 6^2 7^2 then square root it