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3 years ago

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Which of the following does not describe a control group? O A. a group of patients given a new drug B. a group of patients given

a placebo O C. a group of trees not given a new growth hormone O D. a group of students not given a new software package

2 answers:

Setler [38]3 years ago

7 0

Answer:

The answer has to be A

Step-by-step explanation:

The trees have nothing changed about them, so they can be considered to be the control. In additon, placebo is given as a control in medical trials, so it cannot be correct. And, the students have nothing changed in D, so the answer to this question has to be A, where the patients are given a new drug.

Veronika [31]3 years ago

5 0

Answer:

the answer = C (may be but not sure)

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HELP ASAP PLZZZZ

Tcecarenko [31]

QUESTION 1

The given system of equations is

$3d - e = 7...eqn(1)$
$d + e = 5...eqn(2)$

To solve by linear combination, we add equation (1) to equation (2) to get,

$3d + d= 7 + 5$

$4d = 12$

We divide through by 4 to obtain,

$d = \frac{12}{4}$

$d = 3$

We put d=3 into equation (2) to get,

$3+ e = 5$

$e = 5 - 3$

$e = 2$

$\boxed {The \: solution \: is \: (3, 2)}$

QUESTION 2

The given system is

4x + y = 5 ...eqn(1)

3x + y = 3 ...eqn(2)

To solve by linear combination, we subtract equation (2) from equation (1) to eliminate y from the equation.

This will give us,

$4x - 3x = 5 - 3$

This implies that,

$x = 2$

Put x=3 into equation (1) to get,

$4(2) + y = 5$

$8+ y = 5$

$y = 5 - 8$

$y = - 3$

The solution is

$(2,-3)$

QUESTION 3

We want to solve the system;

a – 2b = –2 ....eqn(1)

2a + 2b = 14...eqn(2)

by linear combination.

We need to add equation (1) to equation (2) to eliminate b.

This implies that,

$2a + a = 14 + - 2$

Simplify,

$3a = 12$

Divide both sides by 3 to get,

$a = 4$
Put a=4 into equation (2) to obtain,

$2(4) + 2b = 14$

$8 + 2b = 14$
$2b = 14 - 8$

$2b = 6$

$b = 3$

The ordered pair in the form (a, b) is

$(4,3)$

QUESTION 4

The given system of equations is

11x + 4y = 18 ...eqn(1)

3x + 4y = 2 ...eqn(2)

We subtract equation (2) from equation (1) to get,

$11x - 3x = 18 - 2$

$8x = 16$

$x = 2$

Put x=2 into equation (2) to obtain,

$3(2) + 4y = 2$

This implies that,

$6 + 4y = 2$

$4y = 2 - 6$

$4y = - 4$

$y=-1$

The correct answer is (2,-1).

QUESTION 5

The given system is ;

2d + e = 8...eqn1

d – e = 4...eqn2

We add the two equations to eliminate e.

This implies that,

$2d + d = 8 + 4$

$3d = 12$

We divide both sides by 3 to get,

$d = 4$

We put d=4 into equation (2) to get,

$4 - e = 4$

$- e = 4 - 4$

$- e = 0$

$e = 0$

The solution is

$(4,0)$

7 0

3 years ago

Write an equation for a parabola in which the set of all points in the plane are equidistant from the focus and line F(-6,0); x=

Bogdan [553]

Step-by-step explanation:

Since we have a vertical directrix, the equation of the parabola is

$(y - k) {}^{2} = 4p(x - h)$

Where p is the distance from the vertex to the directrix.

or the distance from the vertex to the focus.

Since we have a sideways parabola, let use the point for the directrix is (-6,0). So let find the midpoint of (-6,0) and (6,0). That would be our vertex.

$\frac{ - 6 + 6)}{2} = 0$

$\frac{0 + 0}{2} = 0$

So our vertex is (0,0).

So our equation become

${y}^{2} = 4px$

The distance from the focus and directrix is 6.

So p=6.

${y}^{2} = 24x$

So p is 6.

Since p is 6,

$\frac{ {y}^{2} }{24} = x$

3 0

2 years ago

Plssss helpppp againnnn

pentagon [3]

Answer:

x = 34°

Step-by-step explanation:

To solve for 'x', we will need to use the Supplementary Angles theorem. This states that on a line, all angles must add up to 180°.

We can set up a simple algebraic equation to solve for 'x':

180 = x + 12 + 100 + x

180 = 112 + 2x **Combine like terms

68 = 2x **Divide both sides by '2'

x = 34°.

Therefore, the measure of ∠x = 34°.

5 0

4 years ago

Read 2 more answers

HI can you help me with this problem?The quantity demanded x for a certain brand of MP3 players is 300 units when the unit price

Vlad [161]

The demand equation is P = -0.05x + 105

STEP - BY - STEP EXPLANATION

What to find?

<em>The demand equation.</em>

The following information is used to solve the problem.

If (x₁ , y₁) and (x₂, y₂) are any dinstinct points on a line a non-vertical line L, then the equation of the line that has a slope(m) and passes through the point (x₁ , y₁) is given by the formula below:

$y-y_1=_{}\frac{y_2-y_1}{x_2-x_1}(x-x_1)$

Assume p, be the unit price and x be the demand when the price is $p.

From the question given, when the unit price x = 300 units, the demand p = $90 and when the unit price x = 1300 units, the demand p = $40

This means the demand curve passes through the points (300, 90) and (1300, 40).

Assume the demand equation is linear, then the line of the equation passes through the points (300, 90) and (1300, 40).

Now;

y=p x₁ =300 y₁ = 90 x₂ = 1300 y₂=40

Substitute the values into the function and simplify.

$p-90=\frac{40-90}{1300-300}(x-300)$

Simplify the above.

$p-90=\frac{-50}{1000}(x-300)$ $p-90=-0.05(x-300)$

Open the parenthesis.

P- 90 = -0.05x + 15

Add 90 to both-side of the equation.

P = -0.05x + 15 + 90

P = -0.05x + 105

Hence, the demand function is P = -0.05x + 105

6 0

1 year ago

Answer me and get brainliest<br><br><br><br>pls find the volume

aalyn [17]

Answer:

6720 ft³

Step-by-step explanation:

Volume = $\frac{1}{2}$ * base * height * length

Here the base is 14 ft, height is 24 ft and length is 40 ft

using the formula:

$\frac{1}{2}$ * 14* 24* 40

6720 ft³

6 0

3 years ago

Read 2 more answers