Answer:
Check your question one time
The temperature of a cup of coffee varies according to Newton's Law of Cooling: -"dT/dt=k(T-A), where is the temperature of the coffee, A is the room temperature, and k is a positive
constant. If the coffee cools from 100°C to 90°C in 1 minute at a room temperature of 25*C, find the temperature, to the nearest degree Celsius of the coffee after 4 minutes,
74
67
60
42
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.
What’s the equation of the line that passes through the point (-4,4) and has a slope of 3/4
Answer:
y-y1=m(x-x1)
y-4=3/4(x+4)
y=3/4x+7
(14) (55, 42, 32, 48, 55, x), mean = 49
Answer:
78
Step-by-step explanation:
Add all the numbers given =256 then take the mean and multiply it with 7 =334 then take 334_256=78 and done
f) 1 5/2 +8x4 =
alluda :(
Answer:
35.5
Step-by-step explanation:
1 5/2 + (8*4)= 35.5
(8*4)= 32
32+1 5/2
1 5/2=3 1/2
32+3 1/3
35.5 or 35 1/2
Help please? thank you
Answer:
Answer is A
Step-by-step explanation:
7. State the type of system of equations.
y + 5x = 6
5y + 25x = 80
Step-by-step explanation:
the systems of equations shown are parallel because they have the same slope
Can some help with this problem
What is 8 x 3 + 10 - 13 x 2? Show your work.
Will give first answer brainliest
Hello!
8 × 3 + 10 - 13 × 2 =
= 24 + 10 - 13 × 2 =
= 24 + 10 - 26 =
= 34 - 26 =
= 8
Good luck! :)
Answer:
8
Step-by-step explanation:
According to bdmas rule
First multiply 8 and 3 or 13 and 2
Then, there will be 24 + 10 - 26
Then add 24 + 10, there will be 34
and again minus by 26
Then finally answer will be 8
How many digits from 10 to 1000 have each digit greater than its following digit?
Answer:
10 has 2 digits
1000 has 4 digits
Difference of 2 digits
Choose the answer that is equivalent to the quotient.
(-4x3 + 16x2 21x + 22) divided by (2x – 3)
0-222 +51 - 3+
13
21-3
o 22 – 3+3
O-212 + 52 - 3+
16
21-3
0-222 + 52 - 3
A sum of money earns the interest ar the rate of Rs. 5 per Rs.25 in a year. how many years would it trible itself?
a. 5
b. 10
c.15
d. 20
Intercept Form
Point (-3,4)
Slope 5
m= b=
Answer:
y = 5x + 19
Step-by-step explanation:
y = 5x + b
4 = 5(-3) + b
4 = -15 + b
19 = b
Please answer fast!!!!!!
The sum of the reciprocals of two consecutive even integers is
9/40. This can be represented by the equation shown.
1/x+1/x+2=9/40
Use the rational equation to determine the integers. Show all work.
Answer:
8 and 10
Step-by-step explanation:
Given
[tex]\frac{1}{x}[/tex] + [tex]\frac{1}{x+2}[/tex] = [tex]\frac{9}{40}[/tex] ← combine the fractions on the left side
[tex]\frac{x+2+x}{x(x+2)}[/tex] = [tex]\frac{9}{40}[/tex]
[tex]\frac{2x+2}{x^2+2x}[/tex] = [tex]\frac{9}{40}[/tex] ( cross- multiply )
9(x² + 2x) = 40(2x + 2) ← distribute both sides
9x² + 18x = 80x + 80 ( subtract 80x + 80 from both sides )
9x² - 62x - 80 = 0
Consider the factors of the product of the coefficient of the x² term and the constant term which sum to give the coefficient of the x- term.
product = 9 × - 80 = - 720 and sum = - 62
The factors are - 72 and + 10
Use these factors to split the x- term
9x² - 72x + 10x - 80 = 0 ( factor the first/second and third/fourth terms )
9x(x - 8) + 10(x - 8) = 0 ← factor out (x - 8) from each term
(x - 8)(9x + 10) = 0
Equate each factor to zero and solve for x
x - 8 = 0 ⇒ x = 8
9x + 10 = 0 ⇒ 9x = - 10 ⇒ x = - [tex]\frac{10}{9}[/tex]
x is an integer , then x = 8 and x + 2 = 8 + 2 = 10
The integers are 8 and 10
Answers: Integers are x=8, x=10.
measured the volume of an object and recorded it as 46 cubic cm
which was 15% high from the actual volume. Find the actual volume.
Answer:
[tex]40\ cm^3[/tex]
Step-by-step explanation:
Let the actual volume is V.
The measured volume of an object is 46 cubic cm which was 15% high from the actual volume.
According to the given condition,
[tex]V+\dfrac{15V}{100}=46\\\\\dfrac{115V}{100}=46\\\\V=\dfrac{4600}{115}\\\\V=40\ cm^3[/tex]
So, the actual volume was [tex]40\ cm^3[/tex].
Calculate cos (theta) to two decimal places. PLS HELP ASAP
Answer:
B. -0.07
Step-by-step explanation:
Apply the Law of signs find θ.
Cos θ = (a² + b² - c²)/2ab
Where,
a = 7
b = 8
c = 11
Plug in the values
Cos θ = (7² + 8² - 11²)/2*7*8
Cos θ = (49 + 64 - 121)/112
Cos θ = -8/112
Cos θ = -0.0714285714
Cos θ = -0.07 (to 2 decimal places)
Describe fully the single transformation that maps a onto shape b
Answer:
Reflected over y-axis
A(-4,-2), B(-1,-1), C(-1,-4)
what are the coordinate of triangle ABC when reflected over the line y=-x?
A). A'(-2,4), B'(1,1), C(-4,1)
B). A'(2,4), B'(1,1), C(4,1)
C). A'(4,2), B'(1,2), C'(2,1)
D). A'(2,4), B'(1,-1),C' (4,-1)
Answer:
B
Step-by-step explanation:
Fip numbers and change both signs when reflecting over y=-x
Answer:
C
Step-by-step explanation:
evaluate f(x)=1/4x for x=-5
option 1. -1/20
option 2. -1 1/4
option 3. 20
option 4. -4/5
Answer:
option 2. -1 1/4
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightAlgebra I
FunctionsFunction NotationStep-by-step explanation:
Step 1: Define
Identify
f(x) = 1/4x
Step 2: Evaluate
Substitute in x [Function f(x)]: f(-5) = 1/4(-5)Multiply: f(-5) = -5/4Simplify: f(-5) = -1 1/4Write a phrase in words to match each expression.
5+3
——
n
Answer:
sum of five and 3 is divided by n
find 22×28×25×30 in acres?
Answer:
22x 28 x 25 x 30 = 462000
whats are the units.....cm or m
[tex]\huge\text{Hey there!}[/tex]
[tex]\large\textsf{22(28)(25)(30)}\\\large\textsf{22(28) = \bf 616}\\\large\textsf{616(25)(30)}\\\large\textsf{616(25) = \bf 15,400}\\\large\textsf{15,400(30)}\\\large\textsf{ = \bf 462,000}\\\\\\\\\\\\\boxed{\boxed{\large\textsf{Answer: \huge \bf 462,000}}}\huge\checkmark[/tex]
[tex]\large\textsf{Good luck on your assignment and enjoy day!}[/tex]
~[tex]\frak{Amphitrite1040:)}[/tex]
Ling must spend no more than $40.00 on decorations for a party. She has spent $10.00 on streamers and wants to buy bags of balloons as well. Each bag of balloons costs $2.50. The inequality below represents x, the number of bags she can buy given the spending limit and how much she has already spent on streamers.
10 + 2.5 x less-than-or-equal-to 40
Which best describes the number of bags of balloons she can buy?
Answer:
She can buy from 0 to 20 bags, but no more.
Answer:
b <3
Step-by-step explanation:
A tower is 543m from your house. The angle of elevation to the top of the tower is 33.4°. How high is the tower?
Answer:
358
Step-by-step explanation:
the step by step is in the photo so look at it
If the ratio of a to b is 2.3 and the ratio
of to bis 3:4, which of the following is
equal to the ratio of a to c.?
Answer:5.7 D
Step-by-step explanation:
Help!!!! hurry quick pls
Answer:
A.
by-step explanation:
m to k
1 to 1.609
f(x)=2x+3/4x+5
find f(-9)
[tex]\implies {\blue {\boxed {\boxed {\purple {\sf { f(-9)= 0.48}}}}}}[/tex]
[tex]\large\mathfrak{{\pmb{\underline{\orange{Step-by-step\:explanation}}{\orange{:}}}}}[/tex]
[tex]f(x) = \frac{2x + 3}{4x + 5} \\[/tex]
For [tex]f(-9)[/tex], put "[tex]-9[/tex]" for every value of "[tex]x[/tex]".
[tex]↬f( - 9) = \frac{2( - 9) + 3}{4( - 9) + 5}\\ [/tex]
[tex]↬ f(-9) = \frac{ - 18 + 3}{ - 36 + 5} \\[/tex]
[tex]↬ f(-9) = \frac{ - 15}{ - 31}\\ [/tex]
[tex]↬ f(-9)= \frac{15}{31}\\ [/tex]
[tex] ↬f(-9)= 0.48\\ [/tex]
[tex]\bold{ \green{ \star{ \red{Mystique35}}}}⋆[/tex]
[tex]\huge\textsf{Hey there!}[/tex]
[tex]\mathsf{f(x) = \dfrac{2x + 3}{4x + 5}}[/tex]
[tex]\mathsf{y = \dfrac{ 2x + 3}{4x + 5}}[/tex]
[tex]\mathsf{y = \dfrac{2(-9) + 3}{4(-9) + 5}}[/tex]
[tex]\mathsf{2(-9)}[/tex]
[tex]\mathsf{\bf = -18}[/tex]
[tex]\mathsf{y = \dfrac{-18 + 3} {4(-9) + 5}}[/tex]
[tex]\mathsf{-18 + 3}\\\mathsf{= \bf -15}[/tex]
[tex]\mathsf{y = \dfrac{ -15} {4(-9) + 5}}[/tex]
[tex]\mathsf{4(-9)}\\\mathsf{\bf = -36}[/tex]
[tex]\mathsf{y = \dfrac{-15}{-36 + 5}}[/tex]
[tex]\mathsf{-36 + 5}\\\mathsf{= \bf-31}[/tex]
[tex]\mathsf{y = \dfrac{-15}{ -31}\rightarrow\boxed{\bf \dfrac{15}{31}}}[/tex]
[tex]\boxed{\boxed{\huge\text{Answer: } \boxed{\bf f(-9) = \dfrac{15}{31}}}}\huge\checkmark[/tex]
[tex]\huge\text{Good luck on your assignment \& enjoy your day!}[/tex]
~[tex]\frak{Amphitrite1040:)}[/tex]
PLZ HELPPP!!!!!!!!!! ASAP
Answer:
They are consecutive terms in the Fibonacci Sequence.
Step-by-step explanation:
The sequence goes 1,1,2,3,5,8,13,21,...
Since 13 and 21 are consecutive here, that is the answer.
Which must be true of a quadratic function whose vertex is the same as its y-intercept?
Answer:
A
Step-by-step explanation:
because y-intercept is when x=0, so right on the y axis.
a. 65
b. 67
c. 43
d. 23
4x⁴+3x²y²+9y⁴
solve by step by step
Answer:
4x^4+3x^2y^2+9y^2
(2x^2)^2 + 2×2x^2×3y^2 + (3y^2)^2 - 9
(2x^2 + 3y^2)^2 - (3)^2
(2x^2 +3y^2+3)(2x^2+3y^3-3)
using the formula of Sin 2A ,cos2a and tan 2a establish that; tab A is = +- root under 1 - cos 2A by 1 + cos 2a
Answer:
Step-by-step explanation:
Given identity is,
[tex]\text{tanA}=\pm\sqrt{\frac{1-\text{cos2A}}{1+\text{cos2A}}}[/tex]
To prove this identity, we will take left side of the identity,
[tex]\pm\sqrt{\frac{1-\text{cos2A}}{1+\text{cos2A}}}=\pm\sqrt{\frac{1-(1-2\text{sin}^2A)}{1+(2\text{cos}^2A-1)} }[/tex]
[tex]=\pm\sqrt{\frac{1-1+2\text{sin}^2A}{1+2\text{cos}^2A-1} }[/tex]
[tex]=\pm\sqrt{\frac{2\text{sin}^2A}{2\text{cos}^2A} }[/tex]
[tex]=\pm(\sqrt{\text{tan}^2A})[/tex]
[tex]=\text{tanA}[/tex] [Right side of the identity]
Hence, proved.