Answer:
B) 67°C.
Step-by-step explanation:
Newton's Law of Cooling is given by:
[tex]\displaystyle \frac{dT}{dt}=k(T-A)[/tex]
Where T is the temperature of the coffee, A is the room temperature, and k is a positive constant.
We are given that the coffee cools from 100°C to 90°C in one minute at a room temperature A of 25°C.
And we want to find the temperature of the coffee after four minutes.
First, solve the differential equation. Multiply both sides by dt and divide both sides by (T - A). Hence:
[tex]\displaystyle \frac{dT}{T-A}=k\, dt[/tex]
Take the integral of both sides:
[tex]\displaystyle \int \frac{dT}{T-A}=\int k\, dt[/tex]
Integrate:
[tex]\displaystyle \ln\left|T-A\right| = kt+C[/tex]
Raise both sides to e:
[tex]|T-A|=e^{kt+C}=Ce^{kt}[/tex]
The temperature of the coffee T will always be greater than or equal to the room temperature A. Thus, we can remove the absolute value:
[tex]\displaystyle T=Ce^{kt}+A[/tex]
We are given that A = 25. Hence:
[tex]\displaystyle T=Ce^{kt}+25[/tex]
Since the coffee cools from 100°C to 90°C, the initial temperature of the coffee was 100°C. Thus, when t = 0,T = 100:
[tex]100=Ce^{k(0)}+25\Rightarrow C=75[/tex]
Hence:
[tex]T=75e^{kt}+25[/tex]
We are given that the coffee cools from 100°C to 90°C after one minute at a room temperature of 25°C.
So, T = 90 given that t = 1. Substitute:
[tex]90=75e^{k(1)}+25[/tex]
Solve for k:
[tex]\displaystyle e^k=\frac{13}{15}\Rightarrow k=\ln\left(\frac{13}{15}\right)[/tex]
Therefore:
[tex]\displaystyle T=75e^{\ln({}^{13}\! /\!{}_{15})t}+25[/tex]
Then after four minutes, the temperature of the coffee will be:
[tex]\displaystyle \begin{aligned} \displaystyle T&=75e^{\ln({}^{13}\! /\!{}_{15})(4)}+25\\\\&\approx 67^\circ\text{C}\end{aligned}[/tex]
Hence, our answer is B.
2. A rectangle has length 13 and width 10. The length and the width of the rectangle are each
increased by 2. By how much does the area of the rectangle increase? *
50
20
38
35
Printed Pages in Color Time (min), x 2 6 8 18 Number of pages, y 3 9 12 27 What is the constant of variation?
Answer:
3/2
Step-by-step explanation:
formula k = y/x
comes from
y = kx
k = constant of variation
when y = 3 , x = 2
k = 3/2
if f(x)= 3^x+10x and g(x)= 2(x) = 2x - 4 find (f+g)(x)
Answer:
(f + g)(x) = 3^x + 12x -4
Step-by-step explanation:
Here, we want to get the value of (f + g)(x)
Mathematically, we have this as;
(f + g)(x) = f(x) + g(x)
= 3^x + 10x + 2x-4
= 3^x + 12x -4
help please
h - (-2) ≥ 10
Answer:
answer
Step-by-step explanation:
h+2 ≥ 10
h ≥ 10 - 2
h ≥ 8
What is the value of x? Show work.
Answer:
x=5
Step-by-step explanation:
This is because the inscribed angle of the circle or angle EFG is equal to the twice of the degree of the arc EG. Therefore, we can create this equation:
12+40=2(8x+10)
12+40=16x+20
20=4x
x=5
For what value of b will f(x) = x^2 + bx + 400 have -20 as its only zero? Record your answer and fill in the bubbles on your answer document.
The polynomials f(x) = x^2 + bx + 400 have -20 as its only zero then the value of b is 40.
The polynomials f(x) = x^2 + bx + 400 have -20 as its only zero
Then x=-20
What is the zero of a polynomial?The zeros of a polynomial p(x) are all the x-values that make the polynomial equal to zero.
x=-20 is the zero of the given polynomial
Therefore it satisfies the given polynomial
[tex]f(-20)=(-20)^2+b(-20)+400[/tex]
[tex]0=400-20b+400\\800-20b=0\\-20b=-800\\b=\frac{-800}{-20} \\b=40[/tex]
Therefore the value of b is 40.
To learn more about the zeros of the polynomials visit:
https://brainly.com/question/12461081
The diagram shows a rectangle. If the perimeter of the rectangle is 66 cm, what is the area of the rectangle?
Answer:
Step-by-step explanation:
Perimeter of the rectangle = P
Base = b
Height = h
Area = A
P = 2b + 2h
P = 66
STEP 1:
2(2x + 1) + 2(x + 5) = 66
Distribute
4x + 2 + 2x + 10 = 66
STEP 2:
Combine like terms and isolate the variable
6x + 12 = 66
6x = 54
x = 9
STEP 3:
Plug in x
A = (2(9) + 1) * (9 + 5)
STEP 4:
Simplify
A = (18 + 1) * (14)
A = (19)(14)
A = 266
[tex]\displaystyle\bf P=2(2x+1+x+5)=66\\\\6x+12=66\\\\6x=54\\\\\boxed{x=9}\\\\2x+1=19\\\\x+5=14 \\\\S=ab=14\cdot19=266 cm^2[/tex]
pls help- the question kept cutting off before:
If cos(πr) = 2 cos(πr) and 0 < r < 3, what is one possible value of r?
Answer:
r can be 0.5
Step-by-step explanation:
Here, we want to get a possible value of r
From the question, the value of r is between 0 and 3
Mathematically, we know that in degrees pi is the same as 180 degrees
In a case where we have r = 1/2
we have it that;
cos(pi/2) = 2 cos (pi/2)
Since pi/2 is 90 and cos 90 is zero; then we have it that the two sides of the equation is the same and r can be 1/2
For the function y=log(x-2)+1 which of the following statements is true? (see picture) (WILL GIVE BRAINLIEST)
Answer:
B.
Step-by-step explanation:
The two
triangles are similar.
What is the value of x?
Enter your answer in the box:
Answer:
x = 5
Step-by-step explanation:
Sides of large triangle: 4x and 15
Corresponding sides of small triangle: 3x + 1 and 12
[tex] \dfrac{4x}{15} = \dfrac{3x + 1}{12} [/tex]
[tex] 60 \times \dfrac{4x}{15} = 60 \times \dfrac{3x + 1}{12} [/tex]
[tex] 16x = 15x + 5 [/tex]
[tex] x = 5 [/tex]
Help, someone please lol
Answer:
2x+5x^2=1
2x+5x*5x=1
2x+25x=1
27x=1
1/27=x
Hope This Helps!!!
Answer:
D. 24
Hope it helps!
There are five students standing in a line with their hats. Suddenly the wind picks up the hats and randomly assigns each hat to a student. What is the probability that no student will get his or her own hat
Answer:
The probability of a person getting their own hat is 1/5 or 20%.
Step-by-step explanation:
If each person has one hat the chances (the probability) of them getting their own hat would be 20%. The chances (the probability) of them getting a hat that belongs to one of the other four students would be 80%. Due to there being 5 hats each person owns 1 hat so there would be a 1 out of 5 chance of them getting their own hat.
Help me please
I will mark you as brainliest
Answer:
In picture
Step-by-step explanation:
Brainliest please~
[tex](0,3)[/tex] and [tex](1,-2)[/tex]
Equation: (refer the image below)
Slope:
[tex]m=\frac{3+2}{0-1}[/tex]
[tex]m=-5[/tex]
Equation:
[tex]y=5x-b[/tex]
[tex]3=b[/tex]
Substitute (0,3)
Point: [tex](1,-2)[/tex]
The mean grade on the statistics exam is M=82, the standard deviation is G=12. What actual grade has a Z score of z= -1.5
Answer:
64
Step-by-step explanation:
-1.5 = (X - 82)12
-18 = X-82
X = 64
What is the Measure of arc XY?
Answer:
Arc XY = 180- 43
= 137º
answer is C
Step-by-step explanation:
What is the scale factor from ABC to DEF?
Within similar triangles, the angles are the same. So, we need to look at the side lengths then.
72 to 12
66 to 11
42 to 7
In each pair of corresponding side lengths, the original side length from triangle ABC is divided by 6 (or multiplied by 1/6) to get the smaller side length on triangle DEF.
The scale factor from ABC to DEF is 1/6.
Hope this helps!
exterior angle equation is 3p-15 interior angles are p and p+15
9514 1404 393
Answer:
p = 30
angles 30°, 45°; exterior: 75°
Step-by-step explanation:
The exterior angle is equal to the sum of the remote interior angle:
3p -15 = p + (p +15)
p = 30 . . . . . . . . . . . . . add 15-2p
The interior angles are 30°, 45°; the exterior angle is 75°.
2(4+2x)≥5x+5 solve inequality
Answer:
x ≤ 3
Step-by-step explanation:
2(4+2x)≥5x+5
8+4x≥5x+5
4x-5x≥5-8
-x≥-3
x ≤ 3
[tex]\tt\displaystyle\2(4+2x)\geq 5x+5\\\\8+4x\geq 5x+5\\\\4x-5x\geq 5-8\\\\-x\geq -3\\\\x\leq 3 \\\\Answer: x\leq 3 \quad or \quad x\in(-\infty;3][/tex]
If AABC IS REFLECTED across the y axis what are the coordinates of A
Answer:
A. (-1, 3)
Step-by-step explanation:
When reflecting across the y-axis: (x, y) ⇒ (-x, y).
Therefore, A(1, 3) ⇒ A'(-1, 3).
Determine the area of the triangle.
67.7 square units
777.2 square units
135.5 square units
5.9 square units
Answer:
cuadradas 777,2 unidades
Step-by-step explanation:
Answer:
67.7
Step-by-step explanation:
i just took the quiz
FACTOR....
x^2 + 10× - 2400 = 0
Answer:
x= -5 + 5[tex]\sqrt{97}[/tex], x= -5 - 5[tex]\sqrt{97}[/tex]
Step-by-step explanation:
Since this quadratic is set to zero, we can use the quadratic formula to solve this.
x^2 + 10x - 2400 = 0
Quadractic formula = x= -b +- [tex]\sqrt{b^2 - 4ac}[/tex] /2a
For this equation:
a= 1, b=10, c=-2400
Plug these numbers into the equation and solve.
x= -10 +- [tex]\sqrt{10^2 - 4(1)(-2400}[/tex])/2(1)
x= -10 +- [tex]\sqrt{100 + 9,600}[/tex]/2
x= -10 +- [tex]\sqrt{9,700}[/tex]/2
x= -10 +- [tex]\sqrt{2^2 * 5^2 * 97}[/tex]/2
x= -10 +- 5 * 2[tex]\sqrt{97}[/tex]/2
x= -10 +- 10[tex]\sqrt{97}[/tex] / 2
Divide by 2.
x= -5 +- 5[tex]\sqrt{97}[/tex]
Answer:
x= -5 + 5[tex]\sqrt{97}[/tex] or x= -5 - 5[tex]\sqrt{97}[/tex]
Determine the solution on the following equation
Answer:
x = 3
Step-by-step explanation:
Step-by-step explanation:
3(8x-8)/2=64
3(8x-8)=64×2
24x-24=128
24x=128+24
24x=152
24x/24=152/24
x=6.3
Solve the qn in attachment .
Answer:
[tex]\implies \dfrac{ -4x+7}{2(x-2) }[/tex]
Step-by-step explanation:
The given expression to us is ,
[tex]\implies \dfrac{\frac{ 3}{x-1} -4 }{ 2 -\frac{2}{x-1}}[/tex]
Now take the LCM as ( x - 1 ) and Simplify , we have ,
[tex]\implies \dfrac{\frac{ 3 -4(x-1) }{x-1} }{ \frac{2-2(2x-1)}{x-1}}[/tex]
Simplifying further , we get ,
[tex]\implies \dfrac{ -4x+7}{2(x-2) }[/tex]
Hence the second option is correct.
Answer:
[tex] \frac{ \frac{3}{x - 1} - 4}{2 - \frac{2}{x - 1} } \\ = \frac{ \frac{3 - 4(x - 1)}{x - 1} }{ \frac{2(x - 1)}{x - 1} } \\ = \frac{3 - 4x + 4}{2x - 2} \\ \frac{ - 4x + 7}{2(x - 1)} \\ option \: b \: is \: your \: answer \\ thank \: you[/tex]
Which of the following shows the coordinates of A (6, 12)
after reflection over the y-axis?
Answer:
(- 6, 12 )
Step-by-step explanation:
Under a reflection in the y- axis
a point (x, y ) → (- x, y ) , then
A (6, 12 ) → A' (- 6, 12 )
the quadratic function f(x) = ax² + bx + c has tge minimum point (-2,-9) ans f(-1) = -7 Find (a) values of a,b and c
i'll mark u brainliest pls,help
Hello again,
"katie deleted your answer to the question Hello,a=2, b=8, c=-1Indeed,y=f(x)=ax...
You've been warned"
Answer is a=2, b=8 and c=-1
Indeed:
y=f(x)=ax²+bx+c
Since (-2,-9) is the vertex,
y=k*(x+2)²-9
Or f(-1)=-7 ==> -7=k*(-1+2)²-9 ==> k=2
f(x)=2(x+2)²-9=2*(x²+4x+4)-9=2x²+8x+8-9
f(x)=2x²+8x-1
A proof: the picture is following.
In an indirect proof, you prove an "if-then" statement is true by assuming the statement is false (stating the inverse or converse), and then disproving the false statement. You want to prove the statement shown below in an indirect proof. What statement should you prove is false?
Statement to Prove True: If a figure has exactly three sides, then it is a triangle.
Statement to Prove False:
Answer:
Step-by-step explanation:
Please help I will mark brainliest- I already know it’s not the last two- please help!
Answer:
Traversable because it has exactly two odd nodes
Step-by-step explanation:
There is a rule that says it is traversable if it has exactly 2 odd nodes. The are other rule where it can be traversable is if has no odd nodes.
Also if we let the starting point be D and the ending point be B we can travel the network in such way that each edge is only traveled once which is the definition that the network is traversable.
So I will do this by starting at D, then travel to A using the outside edge, then travel to back to D using inside edge, then travel to C, then travel to B, then travel to A using outside edge, and then back to B from A using inside edge.
Triangle ABC is congruent to LMN. Find the value of x. Please and thank you!
Warning: if you give an answer that is NOT related to the question at all then I will report you - FIND THE VALUE OF X
Answer:
x = 9
Step-by-step explanation:
The ratios of corresponding sides are equal, that is
[tex]\frac{BC}{MN}[/tex] = [tex]\frac{AB}{LM}[/tex] , substitute values
[tex]\frac{x}{15}[/tex] = [tex]\frac{6}{10}[/tex] ( cross- multiply )
10x = 90 ( divide both sides by 10 )
x = 9
Worth 11 points please help me!
Answer:
124°
I hope it's helps you
HELP ASAP 10 POINTS AND BRAINLIST AND 5 STAR AND THANKS BUT IF CORRECT
Step-by-step explanation:
hope it helps you..........
Answer:
[tex](\frac{2}{5} )^{3}[/tex] = [tex]\frac{8}{125}[/tex] [tex]cm^{3}[/tex]
Step-by-step explanation:
