If 2 students can clean the classroom in 20 min. How long will it take 8 students to clean the classroom?
(1) 160 min
(2) 80 min
(3) 5 min
(4) 10 min

Combine the fractions on the left with a common denominator:

[tex]\dfrac a{x+1} + \dfrac b{x-1} + \dfrac c{(x+1)^2} = \dfrac{a(x+1)(x-1) + b(x+1)^2 + c(x-1)}{(x-1)(x+1)^2}[/tex]

It follows that

[tex]3x^2+3x-2 = a(x+1)(x-1) + b(x+1)^2 + c(x-1)[/tex]

Expand the right side and collect like powers of x :

[tex]3x^2+3x-2 = a(x^2-1) + b(x^2+2x+1) + c(x-1)[/tex]

[tex]3x^2+3x-2 = (a+b)x^2 + (2b + c)x -a +b - c[/tex]

Then we have the system of equations

[tex]\begin{cases}a+b=3\\2b+c=3\\-a+b-c=-2\end{cases}[/tex]

or in matrix form,

[tex]\begin{bmatrix}1&1&0\\0&2&1\\-1&1&-1\end{bmatrix} \begin{bmatrix}a\\b\\c\end{bmatrix} = \begin{bmatrix}3\\3\\-2\end{bmatrix}[/tex]

Compute the determinant of the coefficient matrix:

[tex]\det\begin{bmatrix}1&1&0\\0&2&1\\-1&1&-1\end{bmatrix} = -4[/tex]

Then the inverse of the coefficient matrix is equal 1/det times the adjugate of the coefficient matrix (a.k.a the transpose of the cofactor matrix):

[tex]\begin{bmatrix}1&1&0\\0&2&1\\-1&1&-1\end{bmatrix}^{-1} = \dfrac1{-4} \begin{bmatrix}-3 & -1 & 2 \\ 1 & -1 & -2 \\ 1 & -1 & 2\end{bmatrix}^\top = -\dfrac14 \begin{bmatrix}3&-1&-1\\1&1&1\\-2&2&-2\end{bmatrix}[/tex]

Multiply both sides of the equation by the inverse :

[tex]\begin{bmatrix}a\\b\\c\end{bmatrix} = -\dfrac14 \begin{bmatrix}3&-1&-1\\1&1&1\\-2&2&-2\end{bmatrix} \begin{bmatrix}3\\3\\-2\end{bmatrix} = \begin{bmatrix}2\\1\\1\end{bmatrix}[/tex]

So, we have a = 2 and b = c = 1, and the partial fraction decomposition is

[tex]\dfrac{3x^2+3x-2}{(x+1)^2(x-1)} = \dfrac 2{x+1} + \dfrac 1{x-1} + \dfrac 1{(x+1)^2}[/tex]

Answer:

Step-by-step explanation:

One can solve for a, b, c a little more directly than using a system of 3 equations.

If we multiply the rational expression by (x+1)², we get ...

  (3x² +3x -2)/(x -1) = (x+1)²(a/(x+1) +b/(x-1)) +c

Evaluating this for x = -1 gives ...

  (3(-1)² +3(-1) -2)/(-1 -1) = c

  -2/-2 = 1 = c

Similarly, multiplying by (x -1) gives ...

  (3x² +3x -2)/(x +1)² = (x -1)(a/(x +1) +c/(x +1)²) + b

Evaluating this for x = 1 gives ...

  (3·1² +3·1 -2)/(1 +1)² = b

  4/4 = 1 = b

Now, we need to find the value of 'a'. The identity will hold true for any value of x, so we can see what happens when we substitute x=0. We can use the values of 'b' and 'c' that we found above.

  (3·0² +3·0 -2)/((0 +1)²(0 -1)) = a/(0 +1) +1/(0 -1) +1/(0 +1)²

  -2/-1 = a -1 +1   ⇒   a = 2

_____

System of equations solution

When the terms of the right-side expansion are combined, the numerator of the result is ...

  a(x +1)(x -1) +b(x +1)^2 +c(x -1) = (a+b)x² +(2b+c)x +(-a+b-c) ≡ 3x² +3x -2

Equating the coefficients gives the system of equations whose augmented matrix is:

  [tex]\left[\begin{array}{ccc|c}1&1&0&3\\0&2&1&3\\-1&1&-1&-2\end{array}\right][/tex]

Transforming this to reduced row-echelon form using any of a variety of available tools gives ...

  [tex]\left[\begin{array}{ccc|c}1&0&0&2\\0&1&0&1\\0&0&1&1\end{array}\right][/tex]

which tells you the solution is (A, B, C) = (2, 1, 1).

The confidence interval is between (48.2%, 57.7%)

Using the proportion formula expressed as:

[tex]CI=p\pm z\cdot \sqrt{\frac{p(1-p)}{n} }[/tex]

Get the proportion:

p = 320/600 = 0.53

[tex]z=\frac{x- \mu}{\sigma}[/tex]

[tex]z = \frac{320-240}{47}\\z=\frac{80}{47}\\z= 1.70[/tex]

Substitute into the formula to get the confidence interval to have:

[tex]CI=0.53\pm 1.7\cdot \sqrt{\frac{0.47}{600}}\\CI = 0.53\pm 0.04757\\CI = (0.53-0.04757, 0.53+0.04757)\\CI = (0.482, 0.577)[/tex]

Hence the confidence interval is between (48.2%, 57.7%)

Learn more on  confidence interval here: https://brainly.com/question/20066592

Step-by-step explanation:

x1, x2, x3, x4, x5

(x1 + x2 + x3 + x4 + x5)/5 = 4

x5 - x1 = 6

x3 = 3

2 appears more often than any other number (at least twice), otherwise there would have been multiple modes.

x1 + x2 + x3 + x4 + x5 = 4×5 = 20

x3 = 3

x1 + x2 + 3 + x4 + x5 = 20

x1 + x2 + x4 + x5 = 17

x5 = x1 + 6

x1 + x2 + x4 + x1 + 6 = 17

2×x1 + x2 + x4 = 11

since we did not have the number 2 yet (and we made x5 the harvest number, which has to be larger than 2), and it has to appear at least twice.

so, two numbers out of x1, x2, x3 must be 2. not all three of them can be 2, because 2×2 + 2 + 2 = 8 and not 11 as the last equation demands.

we have therefore 2 different solutions, as either

x1 and x2, or x2 and x4 can be 2.

x1 and x4 is the same solution per the last equation as x1 and x2 (as the variables are interchangeable for the number assignment, only x1 is different, because it has an additional factor in the last equation).

solution 1 (x1 and x2 are 2) :

2×2 + 2 + x4 = 11

4 + 2 + x4 = 11

6 + x4 = 11

x4 = 5

so,

x1 = 2,

x2 = 2,

x3 = 3

x4 = 5

x5 = x1 + 6 = 2 + 6 = 8

solution 2 (x2 and x4 are 2) :

2×x1 + 2 + 2 = 11

2×x1 + 4 = 11

2×x1 = 7

x1 = 7/2

so,

x1 = 7/2

x2 = 2

x3 = 3

x4 = 2

x5 = x1 + 6 = 7/2 + 12/2 = 19/2

Answer:

145% increase

Step-by-step explanation:

343 - 140 = 203

203/140 = 1.45

1.45 x 100 = 145

Part A

The given angle is 4pi/3. Multiply it by the factor 180/pi to convert from radians to degree mode.

Note how the given angle has pi in the numerator, while the conversion factor has pi in the denominator. The two pi terms will cancel.

(4pi/3)*(180/pi)

(4/3)*(180/1)

(4*180)/(3*1)

720/3

240

The angle 4pi/3 radians is equivalent to 240 degrees. This 240 degree angle is in quadrant 3. Any angle in this quadrant is between 180 degrees and 270 degrees, excluding both endpoints. This is the bottom left quadrant, aka the southwest quadrant.

===========================================================

Part B

To find the reference angle, we'll subtract off pi. This only works for angles in quadrant 3. This is because the first pi radians, aka 180 degrees, is taken up by the first two upper quadrants. The remaining bit in the third quadrant is all we care about to find the reference angle.

reference angle = (given angle in quadrant 3) - pi

reference angle = (4pi/3) - pi

reference angle = (4pi/3) - (3pi/3)

reference angle = (4pi - 3pi)/3

reference angle = pi/3

===========================================================

Part C

Use a calculator or a reference table to find that

tan(4pi/3) = tan(pi/3) = sqrt(3)

Alternatively, you can compute the sine and cosine values first

Dividing the two items in the order mentioned will get us the tangent value

tan = sin/cos

tan(pi/3) = sin(pi/3) divide cos(pi/3)

tan(pi/3) = sqrt(3)/2 divide 1/2

tan(pi/3) = sqrt(3)

In the jump from the second to last step, to the last step, the denominators '2' cancel out when dividing.

Answer:

-4 < n ≤5

Step-by-step explanation:

The lower limit is -4.  It has an open circle, so there is no equal sign

-4 < n

The upper limit is 5.  It is a closed circle so there is an equals sign

-4 < n ≤5

Linear equations can represent parallel lines, perpendicular lines and lines with no relationship at all.

The equation of the line in form of y =mx + b is [tex]\mathbf{y = 2x + 17}[/tex]

The equation is given as:

[tex]\mathbf{y =-\frac x2 - 6}[/tex]

For a linear equation y = mx + b, the slope of the equation is m

So, by comparison:

[tex]\mathbf{m =-\frac 12}[/tex]

The relationship between the slopes of perpendicular lines is:

[tex]\mathbf{m_2 =-\frac 1{m_1}}[/tex]

So, we have:

[tex]\mathbf{m_2 =-\frac 1{-1/2}}[/tex]

[tex]\mathbf{m_2 =2 }[/tex]

This means that, the slope of the line that passes through point (-8,1) is 2

The line equation is then calculated as:

[tex]\mathbf{y = m(x - x_1) + y_1}[/tex]

This gives

[tex]\mathbf{y = 2(x + 8) + 1}[/tex]

Open brackets

[tex]\mathbf{y = 2x + 16 + 1}[/tex]

Simplify

[tex]\mathbf{y = 2x + 17}[/tex]

Hence, the equation of the line in form of y =mx + b is [tex]\mathbf{y = 2x + 17}[/tex]

Read more about linear equations at:

https://brainly.com/question/11897796

Answer:

So first you can find a common denominator to make this equation solvable

in this case 4 is the common denominator

2/4+y=5 1/4

Now subtract to isolate the variable (y)

4 3/4 =y

[tex]4^4(4^7)4\implies 4^4\cdot 4^7\cdot 4^1\implies 4^{4+7+1}\implies 4^{12}[/tex]

Answer:

real answer 4^-2

Step-by-step explanation:

just did on edge

Answer:

Step-by-step explanation:

The area A of a rectangle is given by the formula, A=lw , where l is the length and w is the width.

so

8 * 15 = 120sq. units

Answer:

It has to be an isosceles because it has 2 congruent sides (and angles) in the same relative position. The two congruent angles both measure 30 degrees each; the total of degrees in any triangle is always 180. So, the other side has an angle measure of 120 degrees, which is more than 90. Therefore, it is

an obtuse isosceles

Answer:

160000

Step-by-step explanation:

Answer: 2, D

Step-by-step explanation: f=-2, so 4x-2 would give -8 add 10 would give 2 as it is for the negative

Answer:

RS = XY

Step-by-step explanation:

Corresponding sides will be equal. So

RS = XY

[tex](7 + 17 - 14 - 8)q = 14[/tex]

[tex](24 - 22)q = 14[/tex]

[tex]2q = 14[/tex]

Divide both sides by 2

[tex] \frac{2q}{2} = \frac{14}{2} \\ [/tex]

[tex]q = 7[/tex]

There u go...

Have a great day ❤

Using the principle of expected value and discrete probability distribution, the missing values are :

The Expected value, E(X) is defined thus :

The cummulative sum of the probability is 1 :

Hence, we have ;

2** + ** + 0.40 + 0.13 + 0.02 = 1

3** + 0.55 = 1

3** = 1 - 0.55

3** = 0.45

** = 0.45 / 3

** = 0.15

Hence,

* = 2(0.15)

* = 0.30

To find *** :

E(X) = (0 × 0.30) + (1 × 0.15) + (*** × 0.40) + (4 × 0.13) + (5 × 0.02)

12.77 = 0 + 0.15 + 0.40*** + 0.52 + 0.10

12.77 = 0.77 + 0.40***

12.77 - 0.77 = 0.40***

12.00 = 0.40***

*** = 12.00/0.40

*** = 30

B.)

P(1 ≤ Y ≤ 4) = P(y = 1) + P(y = 4)

P(1 ≤ Y ≤ 4) = 0.15 + 0.13 = 0.28

Learn more : https://brainly.com/question/25716562

Answer: The answer would be 3.91666666667

[tex]\huge\textsf{Hey there!}[/tex]

[tex]\mathsf{4 \dfrac{2}{3} - \dfrac{3}{4}}[/tex]

[tex]\mathsf{= \dfrac{4\times3+2}{3} - \dfrac{3}{4}}[/tex]

[tex]\mathsf{= \dfrac{12 + 2}{3} - \dfrac{3}{4}}[/tex]

[tex]\mathsf{= \dfrac{14}{3} - \dfrac{3}{4}}[/tex]

[tex]\mathsf{= \dfrac{56}{11} - \dfrac{9}{12}}[/tex]

[tex]\mathsf{= \dfrac{14\times4}{12 - 0}}[/tex]

[tex]\mathsf{= \dfrac{56 - 9}{12}}[/tex]

[tex]\mathsf{= \dfrac{47}{12}}[/tex]

[tex]\mathsf{= 3 \dfrac{11}{12}}[/tex]

[tex]\huge\textsf{Therefore, your answer should be: }\huge\boxed{\\\mathsf{\dfrac{47}{12} \ or\ 3 \dfrac{11}{12}}}\huge\checkmark[/tex]

[tex]\huge\textsf{Good luck on your assignment \& enjoy your day!}[/tex]

Answer:

2³

Step-by-step explanation:

2×2×2=8

so √8 = 2³

Hope this helps you

Answer:

My man Zachary is right!

Step-by-step explanation:

The rule is so very simple!

Whenever a negative, anywhere in the equation multiples to another negative, it is always a positive!

Whenever a positive number multiples to a negative number anywhere in the equation, it is always a negative number!

So Negative*Negative is Positive (-10 x -10 = 100)

And Positive*Negative is always negative (-10 x 10 = -100)

And we both know that Positive times positive is positive. (10 x 10 = 100)

The scale Trent used for his elementary school which has a school yard of 85

meters wide in real life and 102 millimetre wide in drawing  is 51 : 42500

Firstly, let's do the conversion of the units

1 meters = 1000 millimetres

85 meters = ?

cross multiply

length in millimetres = 85 × 1000 = 85000 millimetres

Since the schoolyard width is 85000 millimetres in real life but it's 102 millimetres wide in drawing , the scale will be as follows:

= 102 / 85000

= 51 / 42500

Therefore, the scale is as follows:

51 : 42500

learn  more: https://brainly.com/question/25328409?referrer=searchResults

A scale is chosen to plot the large graphs on smaller paper representing each unit by a supposed unit.

1.2 mm is used to represent 1 meter.

In the scale given the 102 mm is drawn to represent 85 meters.

So dividing the graph line with the original length the scale Trent has used can be found.

102/85= 1.2

This shows that 1.2 mm is used to represent 1 meter.

Multiplying 85 with 1.2 gives 102 .

https://brainly.com/question/25798457

m = (Y2 - Y1)/(X2 - X1)

m = (-5 - 3)/(-3 - 1)

m = -8/-4

m = 2

Steps are in the attachment.

Note :-

=》2 is taken as negative & also taken out of the square root as it's the common factor.

______

⚜ Hope it helps :))

Answer:

0.5 ㏑ | 1-2x | +c

Step-by-step explanation:

Formula:  ∫ 1/ax+b dx = 1/a ln Iax+bI +c

Answer:

hey you can use scan and search

Answer:

I got : 0.42264973

Step-by-step explanation:

1/ -√3 + 1

-√3 = -1.73 ( 2 decimal place )

1/ -1.73 + 1

and found the answer

Please find attached photograph for your answer.

Hope it helps.

Do comment if you have any query.

Answer:

AB = 23.6

BC = 18.5

CD = 23.6

DA = 18.5

Step-by-step explanation:

4.

Both sets of opposite sides are parallel, so this is a parallelogram.

In parallelogram ABCD:

AB≅CD

AD≅BC

Knowing that, you can write 2 equations with the given information:

[tex]2a-20.4=a+1.6\\a-3.5=18.5[/tex]

You can solve whichever one you want, but I'll do both to be sure.

[tex]2a-20.4=a+1.6\\2a=a+1.6+20.4\\2a-a=1.6+20.4\\a=22[/tex]

Now for the second one:

[tex]a-3.5=18.5\\a=18.5+3.5\\a=22[/tex]

a = 22, so now you can solve for the side lengths.

[tex]2(22)-20.4=23.6\\22-3.5=18.5\\22+1.6=23.6\\18.5=18.5[/tex]

Answer:

69

Step-by-step explanation:

8's     8's+5                 11's     11's+3

8         13                    11          14

16        21                   22         25

24       29                  33          36

32       37                  44          47

40       45                  55          58

48        53                  66         69

56        61                   

64        69

Answer:

5 seconds

Step-by-step explanation:

hope it helps

correct me if i'm wrong