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3 years ago

Solve the following systems using the substitution method.

Mathematics

2 answers:

Inga [223]3 years ago

6 0

Answer:

Step-by-step explanation:

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Nadya [2.5K]3 years ago

6 0

Step-by-step explanation:

2x + 8y = 12 ......... Equation 1

x - 2y = 0 .............. Equation 2

Make x the subject in equation 2 and substitute it into equation 1

That's

x = 2y

We have

2(2y) + 8y = 12

4y + 8y = 12

12y = 12

Divide both sides by 12

y = 1

Substitute y = 1 into x = 2y

That's

x = 2(1)

x = 2

The answers are

x + y = 7......... Equation 1

2x + y = 5 ......... Equation 2

Make y the subject in equation 1 and substitute it into equation 2

We have

y = x - 7

2x + x - 7 = 5

3x = 7 + 5

3x = 12

Divide both sides by 3

x = 4

Substitute x = 4 into y = x - 7

y = 4 - 7

y = - 3

We have the answers as

y = -1/2 + 1 ......... Equation 1

2x + 3y = 6 ........ Equation 2

From equation 1

y = 1/2

Substitute y = 1/2 into Equation 2

So we have

2x + 3(1/2) = 6

2x + 3/2 = 6

2x = 6 - 3/2

2x = 9/2

Divide both sides by 2

x = 9/4

The answers are

2x - 1/3y = - 9.......... Equation 1

-3x + y = 15 ........... Equation 2

Make y the subject in equation 2 and substitute it into equation 1

That's

y = 15 + 3x

2x - 1/3( 15 + 3x) = - 9

2x - 5 - x = - 9

x = - 9 + 5

x = - 4

Substitute x = - 4 into y = 15 + 3x

That's

y = 15 + 3(-4)

y = 15 - 12

y = 3

The answers are

Hope this helps you

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I forgot how to do this man

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3 years ago

In a random sample of students who took the SAT test, 427 had paid for coaching courses and the remaining 2733 had not. Calculat

Dvinal [7]

Answer:

The 95% confidence interval for the proportion of students who get coaching on the SAT is (0.1232, 0.147).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

427 had paid for coaching courses and the remaining 2733 had not.

This means that $n = 427 + 2733 = 3160, \pi = \frac{427}{3160} = 0.1351$

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a p-value of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.1351 - 1.96\sqrt{\frac{0.1351*0.8649}{3160}} = 0.1232$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.1351 + 1.96\sqrt{\frac{0.1351*0.8649}{3160}} = 0.147$

The 95% confidence interval for the proportion of students who get coaching on the SAT is (0.1232, 0.147).

8 0

3 years ago

What number should be added to 77 to make the sum 0?

labwork [276]

You should add -77 to 77 because it will cancel out.

5 0

3 years ago

Read 2 more answers

The question is below the screen

sesenic [268]

9514 1404 393

Answer:

x = 12

Step-by-step explanation:

The square of the length of the tangent segment is equal to the product of lengths from the external common point to the two circle intersections of the secant.

x^2 = (2)(70+2)

x^2 = 144

x = √144

x = 12

4 0

3 years ago

I NEED HELP WITH ME MATH

ruslelena [56]

ok so lets start of with the fact that the whole thing is 21 units.

So we do 21-9=12 so then we now know that the rectangle is 12 so then we do 12*8 units which is= 96 . Now the triangles. so the first one we know that its 8*3 and times it by 1/2 because two triangles is equal to a rectangle so the first triangle is 12 and now the second. its 9-3= 6 then its 6*8*1/2 which is equal to 24 so now the final answer is

96+12+24 which is equal to 132 so i'm guessing it 132 square units

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3 years ago