3.
- 4x + y = 6
- 5x - y = 21

The number of minutes for 20 bacteria be left is 439minutes. The decay constant is 0.0081

An exponential function is a mathematical function, which is used in many real-world situations. It is mainly used to find the exponential decay or exponential growth or to compute investments, model populations and so on.

The No of bacteria left at a particular time t is given as N(t)= Noe^-kt

where No= initial number of bacteria

k= decay constant and t = time

after 13 minutes

630= 700e^-13k

divide both sides by 700

630/700= e^-13k

0.9= e^-13k

ln0.9= -13k

k= ln0.9/-13 = -0.1054/-13 = 0.0081

time for 20 bacteria to be left =

20= 700e^-0.0081t

= 20/700=e^-0.0081t

0.0286= e^-0.0081t

ln0.0286= -0.0081t

-3.554= -0.0081t

divide both sides by -0.0081

t= -3.554/-0.0081= 439 minutes ( nearest minutes)

therefore the time for the bacteria to be left is 439minutes

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Answer: Ten and 91/100.

Step-by-step explanation:

Answer:

XZ ≈ 14.4 cm

Step-by-step explanation:

Using the cosine ratio in the right triangle

cos29° =  =  =  

Multiply both sides by XZ

XZ × cos29° = 12.6 ( divide both sides by cos29° )

XZ =  ≈ 14. 4 ( to 3 sig. figs )

Answer:

14.4

Step-by-step explanation:

Answer:

y= -x-9 because you have to find the negative reciprocal of the slope of the original line and then use the point slope formula y-y1=m(x-x1) to find the perpendicular line

The list of elements in the sets are as follows:

A.  A ∩ B = {2, 9}

B. B ∩ C = {2, 3}

C. A ∪ B ∪ C = {1, 2, 3, 5, 7, 8, 9, 10}

D. B ∪ C = {2, 3, 5, 7, 9, 10}

Set are defined as the collection of objects whose elements are fixed and can not be changed.

Therefore,

universal set = U = {1,2,3, 4, 5, 6, 7, 8, 9, 10​}

A = {1, 2, 7, 8, 9}

B = {2, 3, 5, 9}

C = {2, 3, 7, 10}

Therefore,

A.

A ∩ B = {2, 9}

B.

B ∩ C = {2, 3}

C.

A ∪ B ∪ C = {1, 2, 3, 5, 7, 8, 9, 10}

D.

B ∪ C = {2, 3, 5, 7, 9, 10}

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The required reverse Euclidean algorithm is the solution to the modular equation (5x) mod 91 is

x = 6(mod 91).

Given that (5*x) mod 91 =32.

To solve the modular equation (5*x) mod 91 =32 using reverse Euclidean algorithm is to find the modular inverse of 5 modulo 91.

Consider  (5*x) mod 91 =32.

5x = 32(mod 91)

Apply the Euclidean algorithm to find GCD of 5 and 91 is

91 = 18 * 5 + 1.

Rewrite it in congruence form,

1 = 91 - 18 *5

On simplifying the equation,

1 = 91 (mod 5)

The modular inverse of 5 modulo 91 is 18.

Multiply equation by 18 on both sides,

90x = 576 (mod91)

To obtain the smallest positive  solution,

91:576 = 6 (mod 91)

Divide both sides by the coefficient of x:

x = 6 * 90^(-1).

Apply the Euclidean algorithm,

91 = 1*90 + 1.

Simplify the equation,

1 + 1 mod (90)

The modular inverse of 90 modulo 91 is 1.

Substitute the modular inverse in the given question gives,

x = 6*1(mod 91)

x= 6 (mod91)

Therefore, the solution to the modular equation (5x) mod 91 is

x = 6(mod 91).

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The graph that correctly shows the boundary line for y ≤ 2x − 4, is B. Graph B.

The inequality y ≤ 2x − 4, shows that the y - intercept is - 4. What this means is that the boundary line must pass through ( 0, - 4 ). As Graphs C and D do not cross ( 0, - 4 ), neither of them can be the boundary line.

Also, when representing an inequality on a graph, the signs of ≤ and ≥ are presented with a solid line. > and < are the ones presented with a broken line. This means that Graph A cannot the boundary line for the inequality.

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The correct order of reasons that complete the proof about the rectangle and square is that D. definition of congruence, distance formula if two consecutive sides of a rectangle are congruent, then it's a square.

It should be noted that congruence simply means an agreement or a correspondence between shapes.

In geoemtry, it should be noted that figures are said to be congruent if it is possible to superpose one of them on another.

It should be noted that the opposite sides of a rectangle are parallel while in a square, all the sides that are given are equal.

Therefore, the correct order of reasons that complete the proof about the rectangle and square is the definition of congruence, and that if two consecutive sides of a rectangle are congruent, then it's a square.

In conclusion, the correct option is D.

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According to the information we can infer that the period of the graph is 8.

To determine the period of the graph we have to consider that the period of a grah is the distance between rigdes. So, in this case we have to count what is the difference between each rigde.

In this case, the distance between rigdes is 8 units because the first is located in the line 1 an the second is located in the line 9. So we can conclude that the period of the graph is 8.

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Answer:

925.04cm²

Step-by-step explanation:  

Curved surface area of a cylinder = 2πrh

If the sum of the radius of the base and height of the cylinder is 21 cm, then;

r + h = 21

r = 21-h..... 1

The curved surface area is expressed according to the formula

CSA =  2πrh

Substitute the value of CSA given into the formula

616 = 2πrh ....2

Substitute equation 1 into 2;

]616 = 2π(21-h)h

616 = 2π(21h-h²)

Note that π = 3.14

616 = 42(3.14)h - 2(3.14)h²

616 = 131.88h - 6.28h²

98.09 = 21h - h²

h²-21h+98.09 = 0

h = 21±√21²-4(98.09)/2

h = 21±√441-392.36/2

h = 21±√48.64/2

h = 21±6/97/2

h = 21+6.97/2 and 21-6.97/2

h = 27.97/2 and 14.03/2

h = 13.985 and 7.015

Recall that r = 21-h

r = 21 - 13.985

Substitute r = 7.015  into the total surface area of the cylinder

The total surface area = 2πrh + 2πr²

The total surface area = 616 + 2(3.14)7.015²

The total surface area = 616 + 309.04

The total surface area = 925.04

Hence the total surface area of the cylinder is 925.04cm²

Answer:

option 2

Step-by-step explanation:

The graphs intersect at x=-4 and x=0.

The correct answer is option (A) TH. The diameter of the circle shown in the diagram is TH

A diameter is a straight line that passes through the center of the circle and connects two points on the circle.

Therefore, in order to find the diameter of a circle, we need to identify two points on the circumference that are opposite to each other.

These two points form the endpoints of the diameter of the circle.

The given circle is shown below: As we can see from the diagram, points H and T lie on the circumference of the circle, and they are opposite to each other.

Hence, the line TH is the diameter of the circle.

Therefore, the correct answer is option (A) HT, which represents the diameter of the circle shown in the diagram.

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Answer:

24.4

Step-by-step explanation:

just did it delta

Answer: the opposite of 15

Step-by-step explanation:

Every number 'a' on number line is exactly opposite of '-a'.

So, 15 is the opposite of '-15'

Also absolute value for any number gives its positive value, soabsolute value of 15 = 15

Moving 0 to 15 gives the  distance between zero and 15.

So all statements are true except "the opposite of 15".

Hence, the required statement is "the opposite of 15".

Answer:

  SSS congruence

Step-by-step explanation:

All sides of a rhombus are the same length. The diagonal AC is congruent to itself, so ΔABC ≅ ΔCDA by the SSS congruence postulate.

Answer:

C. -4

Step-by-step explanation:

65+79+40+x=180 because sum if angles in a triangle is equal to 180

184+x=180

x=180-184

x=-4

Using trigonometric identities, we found that sec Φ = -7/(2√10), sin Φ = 3/7, tan β = √11/5, and sin β = √11/6 for the given values of csc Φ, cot Φ, and sec β.

1. We can start by using the Pythagorean identity to find the values of sin Φ:

\(sin^2\) Φ + \(cos^2\) Φ = 1

Since csc Φ = 1/sin Φ, we can substitute and solve for sin Φ:

1/(7/3) = sin Φ

sin Φ = 3/7

Next, we can use the fact that cot Φ = cos Φ/sin Φ:

cot Φ = cos Φ/(3/7) = - (2√10)/(3)

Simplifying this expression, we get:

cos Φ = - (2√10)/(3) * (3/7) = - 2√10/7

Finally, we can use the fact that sec Φ = 1/cos Φ:

sec Φ = 1/(- 2√10/7) = -7/(2√10)

2. We can use the fact that sec β = 1/cos β to find the value of cos β:

sec β = 6/5

cos β = 5/6

Next, we can use the Pythagorean identity to find the value of sin β:

\(sin^2\) β + \(cos^2\) β = 1

sin β = √(1 - \(cos^2\) β) = √(1 - 25/36) = √(11/36) = √11/6

Finally, we can use the fact that tan β = sin β/cos β:

tan β = (√11/6)/(5/6) = √11/5

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Answer: Go here https://quickmath.com/webMathematica3/quickmath/equations/solve/basic.jsp

Step-by-step explanation:

It will show you how

The new price of the item is equivalent to $3.25.

Given is that the price of an item has been reduced by 95%. The original price was $65

Assume the new price to be $[x]. So, we can write -

x = 65 - {95% of 65}

x = 65 - {(95/100) x 65}

x = 65 - {6175/100}

x = 65 - 61.75

x = 3.25

Therefore, the new price of the item is equivalent to $3.25.

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Answer:

B) 6

Step-by-step explanation:

Let the number be x

Product of 6 and square of number plue 15 : (6x²) + 15

Coefficient of x² = 6

Answer:

15.5

Step-by-step explanation:

Pepe= 2/3 x 12 = 8

Paula= 1/4 x 30 = 7.5

8+7.5=15.5

Answer:

Ron has 15 nickels and 9 quarters

Step-by-step explanation:

Create a system of equations where n is the number of nickels and q is the number of quarters he has:

n + q = 24

0.05n + 0.25q = 3

Solve by elimination by multiplying the top equation by -0.25

-0.25n - 0.25q = -6

0.05n + 0.25q = 3

Add them together and solve for n:

-0.2n = -3

n = 15

So, Ron has 15 nickels. Find how many quarters he has by subtracting 15 from 24:

24 - 15

= 9

So, Ron has 15 nickels and 9 quarters.

The key features of the dashed graph are

A graph is a pictorial representation of a function

To describe the key features of the dashed graph, we proceed as follows.

So, the key features of the dashed graph are

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Ok, so

We got these facts:

The number of customers that paid cash: 85

The number of customers that used a debit card: 4

The number of customers that used a credit card: 12

Now, it would be useful to find the total number of different payments made, which is: 85 + 4 + 12, and this is 101 payment.

Remember that:

Probability = The number of desired outcome/(The number of possible outcome)

The probability that the next customer will pay with something other than a debit card = (The number of customers that used something different than a credit card) / (The total number of different payments made)

So, Probability = (85+12) / 101

And this is Probability = 97/101

For the second question:

We know that the total students asked from eighth are 29. So, the probability that an eighth grader chosen at random will play an instrument other than guitar, will be:

Probability = 22/29

The symbolic quantified statement is given as:

For all real integers x and y, if x³ = y³, then x = y.

Using quantifiers, this can be written as:

∀x,y∈ℝ, (x³ = y³) → (x = y)

The symbolic quantified statement represents the original sentence using logical symbols and quantifiers.

The universal quantifier (∀) is used to denote "for all," while the implication arrow (→) represents "if... then." The statement asserts that if the cubes of any two real integers x and y are equal, then x and y are equal as well.

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Answer:

The answer is 7.1cm to 1d.p

Step-by-step explanation:

Area of square =L²

25=L²

√L²=√25

L=5cm

hyp²=opp²+adj²

x²=5²+5²

x²=25+25

x²=50

√x²=√50

x=7.1cm to 1d.p

Answer:

342 square meters

Step-by-step explanation:

Consider the length of j;

\(j * 9 * 9 = 405,\\j = 405 / 81,\\j = 5 meters\)

Applying the volume of a rectangular prism formula length * width * height = volume, we noted that 9, 9, and j corresponded to the length, width, and height of the rectangular prism and made it equivalent to the volume. Doing so, we solved for j. Now let us solve for the surface area;

\(Area of 1st Face = 5 * 9 = 45,\\Area of 2nd Face = 9 * 9 = 81,\\Area of 3rd Face = 5 * 9 = 45,\\\\Surface Area = 2 * ( 45 ) + 2 * ( 81 ) + 2 * ( 45 ) = 342 square meters\)

Opposite faces are equal in terms of their area, so by finding the area of 3 faces, we multiply their area each by 2 to result in the total surface area!