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3 years ago

Helppp please I’m desperate

Mathematics

1 answer:

IRINA_888 [86]3 years ago

7 0

The elimination method works by adding the two equations and eliminating one variable. Then you solve an equation in one variable. Finally, you use substitution or elimination again to find the other variable. Sometimes, by simply adding the equations, a variable is not eliminated. Then you need to multiply one or both equations by a factor to get a variable to be eliminated.

A)
2x - 4y = 8
x + 3y = -11

Adding the equations does not eliminate x or y.
Notice that in the first equation, every coefficient is even. We can divide both sides of the first equation by 2. Then the first term would be x. Instead, let's divide both sides of the first equation by -2. Then the x's will be eliminated.

-x + 2y = -4   <-- The first equation divided by -2
x + 3y = -11 <-- The original second equation. Now we add the equations.
----------------
      5y = -15

        y = -3

Now that we know y = -3, we substitute it into the first original equation and solve for x.

2x - 4y = 8

2x - 4(-3) = 8

2x + 12 = 8

2x = -4

x = -2

Answer: x = -2; y = -3

B)
We see that the x's will be eliminated by addition. Just add the equations.

-3x + 7y = 9
3x - 7y = 1
---------------
   0 + 0   = 10

0 = 10 <---- this is a false statement, so this system of equations has no solution.

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mars1129 [50]

Answer:

Step-by-step explanation:

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3 years ago

Samara buys a video game for $56.00 she also buys a book. The price of video game is 8 times as much as the price of the book. W

igor_vitrenko [27]

The answer is $7.00 because 56.00/8=7.00.
Hope that helps.

4 0

3 years ago

Read 2 more answers

WHAT IS 3/8 DIVIDED BY 1/2

serious [3.7K]

Answer: 3/4

Step-by-step explanation: Dividing by a fraction is the same as multiplying by its reciprocal. In other words, we can change the divison sign to multiplication and flip the second fraction.

So here, 3/8 divided by 1/2 can be rewritten as 3/8 × 2/1.

Now we are simply multiplying fractions so we multiply across the numerators and we multiply across the denominators.

So we have 3 × 2 which is 6 and 8 × 1 which is 8. Since 6/8 is not in lowest terms, we divide the numerator and the denominator by the greatest common factor of 6 and 8 which is 2 and we get the equivalent fraction 3/4.

Therefore, 3/8 divided by 1/2 is 3/4.

7 0

3 years ago

Eliza is two years younger than half her brother, Juan’s age. Write an equation to represent Eliza’s age. If Juan is 6 how old i

Natalka [10]

X = Juan's age
y = Eliza's age

Some key words/phrases we can use to help us make the equation are:

-is (whatever comes after this word usually equals the end result, or what it equals)
-two years younger
-than
-half her brother's age
.
just break it down :)

x/2 (half her brother's age) - 2 (two years younger) = y (Eliza is...)

| basically,
v

x/2 - 2 = y
So if Juan is 6, then we need to plug in 6 for x.

6/2 - 2 = y

3 - 2 = y

1 = y

ANSWER: Eliza is one year old.

6 0

3 years ago

A laboratory scale is known to have a standard deviation (sigma) or 0.001 g in repeated weighings. Scale readings in repeated we

weqwewe [10]

Answer:

99% confidence interval for the given specimen is [3.4125 , 3.4155].

Step-by-step explanation:

We are given that a laboratory scale is known to have a standard deviation (sigma) or 0.001 g in repeated weighing. Scale readings in repeated weighing are Normally distributed with mean equal to the true weight of the specimen.

Three weighing of a specimen on this scale give 3.412, 3.416, and 3.414 g.

Firstly, the pivotal quantity for 99% confidence interval for the true mean specimen is given by;

P.Q. = $\frac{\bar X - \mu}{\frac{\sigma}{\sqrt{n} } }$ ~ N(0,1)

where, $\bar X$ = sample mean weighing of specimen = $\frac{3.412+3.416+3.414}{3}$ = 3.414 g

$\sigma$ = population standard deviation = 0.001 g

n = sample of specimen = 3

$\mu$ = population mean

<em>Here for constructing 99% confidence interval we have used z statistics because we know about population standard deviation (sigma).</em>

So, 99% confidence interval for the population mean, $\mu$ is ;

P(-2.5758 < N(0,1) < 2.5758) = 0.99 {As the critical value of z at 0.5% level

of significance are -2.5758 & 2.5758}

P(-2.5758 < $\frac{\bar X - \mu}{\frac{\sigma}{\sqrt{n} } }$ < 2.5758) = 0.99

P( $-2.5758 \times {\frac{\sigma}{\sqrt{n} } }$ < ${\bar X - \mu}$ < $2.5758 \times {\frac{\sigma}{\sqrt{n} } }$ ) = 0.99

P( $\bar X-2.5758 \times {\frac{\sigma}{\sqrt{n} } }$ < $\mu$ < $\bar X+2.5758 \times {\frac{\sigma}{\sqrt{n} } }$ ) = 0.99

<u>99% confidence interval for</u> $\mu$ = [ $\bar X-2.5758 \times {\frac{\sigma}{\sqrt{n} } }$ , $\bar X+2.5758 \times {\frac{\sigma}{\sqrt{n} } }$ ]

= [ $3.414-2.5758 \times {\frac{0.001}{\sqrt{3} } }$ , $3.414+2.5758 \times {\frac{0.001}{\sqrt{3} } }$ ]

= [3.4125 , 3.4155]

Therefore, 99% confidence interval for this specimen is [3.4125 , 3.4155].

6 0

3 years ago