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3 years ago

7

how do I solve this quadratic simultaneous equation 2y+2x=7 and x^2-4y^2=8 it has two sets of solutions and I'm solving by both

variables

2 answers:

Maksim231197 [3]3 years ago

8 0

Sent a picture of the solution to the problem (s).

Ghella [55]3 years ago

3 0

These are all the possible answers i know from experience.

2x + 2y = 7
x^2 - 4y^2 = 8

2x = -2y + 7
x = -y + 7/2

(-y + 7/2)^2 - 4y^2 = 8

y^2 - 7y + 49/4 - 4y^2 = 8

0 = 3y^2 + 7y + 8 - 49/4

0 = 12y^2 + 28y + 32 - 49

0 = 12y^2 + 28y - 17

y = (-b ± √(b^2 - 4ac))/(2a)

y = (-28 ± √(28^2 - 4(12)(-17)))/(2(12))

Dividing by 2 is like dividing by √(4):

y = (-14 ± √(7*28 + (12)(17)))/(2*6)

y = (-7 ± √(7*7 + (3)(17)))/6

y = (-7 ± 10)/6 = 1/2 or -17/6

x = -y + 7/2 = 3 or 19/3

<span>Solutions are (3,1/2) and (19/3,-17/6)</span>

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The rectangle shown has a perimeter of 86 cm and the given area. Its length is 7 more than five times its width. Write and

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Answer: the length of the rectangle is 37ft

the width of the rectangle is 6 ft

Step-by-step explanation:

Let L represent the length of the rectangle.

Let W represent the width of the rectangle.

The formula for determining the perimeter of a rectangle is expressed as

Perimeter = 2(L + W)

The perimeter of the given rectangle is 86 feet. This means that

2(L + W) = 86

Dividing through by 2, it becomes

L + W = 43 - - - - - - - - - - - -1

Its length is 7 more than five times its width.. This means that

L = 5W + 7

Substituting L = 5W + 7 into equation 1, it becomes

5W + 7 + W = 43

6W + 7 = 43

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3 0

3 years ago

The number of girl child per family was recorded for 1000 families with 3 children. The data obtained was as follows: [2] Number

ira [324]

Answer:

$a.\ Probability = 0.426$

$b.\ Probability = 0.574$

Step-by-step explanation:

Given

$Total\ Families = 1000$

Number of Girls : 0 ----> 1 -----> 2 ------->3

Number of Families: 112 -> 314 --> 382 ---> 192

Solving (a): At most one girl

From the table, the number of families with at most one girl is: 112 + 314

i.e.

Number of Girls : 0 ----> 1

Number of Families: 112 -> 314

So, we have:

$At\ Most\ One\ Girl = 112 + 314$

$At\ Most\ One\ Girl = 426$

The probability is then calculated as:

$Probability = \frac{At\ Most\ One\ Girl}{Total}$

$Probability = \frac{426}{1000}$

$Probability = 0.426$

Solving (b): More girls

From the table, the number of families with more girl is: 382 + 192

i.e.

Number of Girls : -----> 2 ------->3

Number of Families: --> 382 ---> 192

So, we have:

$More\ Girls = 382 + 192$

$More\ Girls = 574$

The probability is then calculated as:

$Probability = \frac{More\ Girls}{Total}$

$Probability = \frac{574}{1000}$

$Probability = 0.574$

4 0

3 years ago

A right triangle has an angle that measures 47°. What is the measurement of the third angle in the triangle?

Allushta [10]

Answer:

43 degrees

Step-by-step explanation:

every triangle all three angles equal 180 for a right triangle you know that one angle is 90 degrees for this triangle we know that another angle is 47 so

90+47 = 137 now we can take 180 - 137 = 43

so your third angle is 43

hope I helped!!

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3 years ago

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The constant is 5. :)

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3 years ago

Read 2 more answers

A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at th

Valentin [98]

Answer:

$\bar X= \sum_{i=1}^n \frac{x_i}{n}$ (2)

$s=\sqrt{\frac{\sum_{i=1}^n (x_i-\bar X)}{n-1}}$ (3)

The mean calculated for this case is $\bar X=12.8$

The sample deviation calculated $s=4.324 \approx 4.3$

$12.8-4.604\frac{4.324}{\sqrt{5}}=3.896$

$12.8+ 4.604\frac{4.324}{\sqrt{5}}=21.704$

So on this case the 99% confidence interval would be given by (3.896;21.704)

Step-by-step explanation:

Data: 10,9,20,13,12

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

In order to calculate the mean and the sample deviation we can use the following formulas:

$\bar X= \sum_{i=1}^n \frac{x_i}{n}$ (2)

$s=\sqrt{\frac{\sum_{i=1}^n (x_i-\bar X)}{n-1}}$ (3)

The mean calculated for this case is $\bar X=12.8$

The sample deviation calculated $s=4.324$

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=5-1=4$

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,4)".And we see that $t_{\alpha/2}=4.604$

Now we have everything in order to replace into formula (1):

$12.8-4.604\frac{4.324}{\sqrt{5}}=3.896$

$12.8+ 4.604\frac{4.324}{\sqrt{5}}=21.704$

So on this case the 99% confidence interval would be given by (3.896;21.704)

6 0

3 years ago