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Charra [1.4K]
3 years ago
7

I DONT KNOW THESE! HELP!

Mathematics
1 answer:
kkurt [141]3 years ago
3 0

Answer:

20. x = 5, y = -2

21. x = 11, y = 12

22. x = 22, y = 11

23. x = 11, y = 10

Step-by-step explanation:

20. Opposite sides in the parallelogram are congruent, so

2y+18=3x-1\\ \\6x-3=17-5y

Solve this system of two equations:

\left\{\begin{array}{l}2y-3x=-19\\ \\6x+5y=20\end{array}\right.

Multiply the first equation by 2 and add two equations:

2(2y-3x)+6x+5y=2\cdot (-19)+20\\ \\4y-6x+6x+5y=-38+20\\ \\9y=-18\\ \\y=-2

Substitute it into the first equation:

2\cdot (-2)-3x=-19\\ \\-3x=-19+4\\ \\-3x=-15\\ \\x=5

21. Opposite angles in the parallelogram are congruent, so

11x+5=10y+6

Consecutive angles are supplementary, so

6x-y+11x+5=180^{\circ}

Solve this system of two equations:

\left\{\begin{array}{l}11x-10y=1\\ \\17x-y=175\end{array}\right.

From the second equation

y=17x-175

Substitute it into the first equation:

11x-10(17x-175)=1\\ \\11x-170x+1750=1\\ \\-159x=-1749\\ \\x=11\\ \\y=17\cdot 11-175=187-175=12

22. Opposite angles in the parallelogram are congruent, so

2x-5=3y-12

Consecutive angles are supplementary, so

2x-5+7y+x=180^{\circ}

Solve this system of two equations:

\left\{\begin{array}{l}2x-3y=-7\\ \\3x+7y=185\end{array}\right.

From the first equation

x=-3.5+1.5y

Substitute it into the second equation:

3(-3.5+1.5y)+7y=185\\ \\-10.5+4.5y+7y=185\\ \\-105+45y+70y=1,850\\ \\115y=1,850+105\\ \\115y=1,955\\ \\y=17\\ \\x=-3.5+1.5\cdot 17=22

23. Opposite sides in the parallelogram are congruent, so

2x+9=4y-9\\ \\3x-5=2y+8

Solve this system of two equations:

\left\{\begin{array}{l}2x-4y=-18\\ \\3x-2y=13\end{array}\right.

Multiply the second equation by 2 and subtract it from the first equation:

2x-4y-2(3x-2y)=-18-2\cdot 13\\ \\2x-4y-6x+4y=-18-26\\ \\-4x=-44\\ \\x=11

Substitute it into the first equation:

2\cdot 11-4y=-18\\ \\-4y=-18-22\\ \\-4y=-40\\ \\y=10

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<em>This means that at some specific number of days the cost for Oceanview and  Beachside will be the same.</em>

<h2 /><h2>Explanation:</h2>

See the complete question in the attached file. In this exercise, we know that Oceanview charges $100 per day plus a one-time fee of $40. This can be represented by the following equation:

Total cost for Oceanview:

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So we have to explain what the equation:

110d=100d+40

represents in the context of the problem. We have used substitution in order to get that equation, so <em>this means that at some specific number of days the cost for Oceanview and  Beachside will be the same.</em>

This value was calculated and we get that<em> the cost at the hotels will be the same after 4 days and it will be $440.</em>

<h2>Learn more:</h2>

Linear equations: brainly.com/question/12412678

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A doctoral student wants to determine the relationship between steps per minute and the time it takes to walk 100 feet in
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Using correlation coefficients, it is found that that the correct option is given as follows:

The correlation would stay the same because the change in units for time would have no effect on it.

<h3>What is a correlation coefficient?</h3>
  • It is an index that measures correlation between two variables, assuming values between -1 and 1.
  • If it is positive, the relation is positive, that is, they are direct proportional. If it is negative, they are inverse proportional.
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The correlation coefficient does not have units, hence if the units of the measures is changed, the coefficient remains constant, which means that the correct option is given by:

The correlation would stay the same because the change in units for time would have no effect on it.

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Answer:

<em><u>B. Store T sells apples at the lowest rate</u></em>

Step-by-step explanation:

Store R sells apples at $1.20 <u>per pound.</u>

Store S sells <u>4 pounds</u> of apples at $5.00.

Store T sells <u>3 pounds</u> of apples at $3.48.

To find the answer, <u>you have to find the unit price</u> for both Store S and Store T.

For Store S: 4 pounds = $5. <u>Divide the cost by the pounds</u>. This will give us <u>$1.25 per pound.</u>

For Store T: 3 pounds = $3.48. Same thing as Store S, d<u>ivide the cost by the number of pounds</u>. This will give us <u>1.16 per pound</u>.

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This answer is <em><u>correct</u></em>, but I'll also take a look at the other two

C. Store S charges a lower rate for apples than Store T.

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D. Store T charges the same rate for apples as Store R.

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<h2>I hope this helped you understand the question!</h2>
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