Please help me ASAP!!!

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.

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].

Answer:

y-y1=m(x-x1)

y-4=3/4(x+4)

y=3/4x+7

Answer:

A.

by-step explanation:

m to k

1 to 1.609

Answer: [tex]\frac{5}{9}\ m[/tex]

Step-by-step explanation:

Given

Area of the rectangular piece of paper is [tex]A=\frac{1}{3}\ m^2[/tex]

Length of the paper is [tex]l=\frac{3}{5}\ m[/tex]

Suppose width of the paper is [tex]w[/tex]

Area is the multiplication of length and width

[tex]\therefore A=lw\\\\\Rightarrow \dfrac{1}{3}=\dfrac{3}{5}\times w\\\\\Rightarrow w=\dfrac{5}{9}\ m[/tex]

Thus, the width of the paper is [tex]\frac{5}{9}\ m[/tex]

Answer:

Answer is A

Step-by-step explanation:

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)

Answer:

[tex]A=157.07\ cm^2[/tex]

Step-by-step explanation:

Given that,

The radius of a cylinder, r = 5 cm

Height of the cylinder, h = 5 cm

We need to find the lateral surface area of the  cylinder. The formula for the lateral surface area of the cylinder is given by :

[tex]A=2\pi r h[/tex]

Put all the values,

[tex]A=2\pi\times 5\times 5\\\\=157.07\ cm^2[/tex]

So, the lateral surface area of the cylinder is [tex]157.07\ cm^2[/tex].

Answer:

358

Step-by-step explanation:

the step by step is in the photo so look at it

Answer:5.7 D

Step-by-step explanation:

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

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.

Answer:

She can buy from 0 to 20 bags, but no more.

Answer:

b <3

Step-by-step explanation:

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)

Answer:

sum of five and 3 is divided by n

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.

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

Answer:

B

Step-by-step explanation:

Fip numbers and change both signs when reflecting over y=-x

Answer:

C

Step-by-step explanation:

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.

Answer:

Reflected over y-axis

Answer:

A

Step-by-step explanation:

because y-intercept is when x=0, so right on the y axis.

Answer:

y = 5x + 19

Step-by-step explanation:

y = 5x + b

4 = 5(-3) + b

4 = -15 + b

19 = b

Answer:

10 has 2 digits

1000 has 4 digits

Difference of 2 digits

[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]

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]

Step-by-step explanation:

the systems of equations shown are parallel because they have the same slope