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4 years ago

Use the elimination method to solve the system of equations.

Mathematics

1 answer:

ExtremeBDS [4]4 years ago

4 0

Answer:

Option D. (8, – 4)

Step-by-step explanation:

3x + 4y = 8 ..... (1)

x – y = 12.... (2)

To solve the above equation by elimination method, do the following:

Step 1:

Multiply equation 1 by the coefficient of x in equation 2 i.e 1.

Multiply equation 2 by the coefficient of x in equation 1 i.e 3. This is illustrated below:

1 × Equation 1

1 × (3x + 4y = 8)

3x + 4y = 8 ...... (3)

3 × Equation 2

3 × ( x – y = 12)

3x – 3y = 36......(4)

Step 2:

Subtract equation 3 from equation 4. This is illustrated below:

. 3x – 3y = 36

– (3x + 4y = 8)

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

– 7y = 28

Divide both side by the coefficient of y i.e –7

y = 28/–7

y = – 4

Step 3:

Substitute the value of y into any of the equation to obtain the value of x. In this case, we shall substitute the value of y into equation 2 as shown below:

x – y = 12

y = –4

x – (–4) = 12

x + 4 = 12

x = 12 – 4

x = 8

Therefore, the solution to the equation above is (8, – 4)

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In a certain community, 36 percent of the families own a dog and 22 percent of the families that own a dog also own a cat. In ad

zysi [14]

Answer: a) 0.0792 b) 0.264

Step-by-step explanation:

Let Event D = Families own a dog .

Event C = families own a cat .

Given : Probability that families own a dog : P(D)=0.36

Probability that families own a dog also own a cat : P(C|D)=0.22

Probability that families own a cat : P(C)= 0.30

a) Formula to find conditional probability :

$P(B|A)=\dfrac{P(A\cap B)}{P(A)}\\\\\Rightarrow P(A\cap B)=P(B|A)\times P(A)$ (1)

Similarly ,

$P(C\cap D)=P(C|D)\times P(D)\\\\=0.22\times0.36=0.0792$

Hence, the probability that a randomly selected family owns both a dog and a cat : 0.0792

b) Again, using (2)

$P(D|C)=\dfrac{P(C\cap D)}{P(C)}\\\\=\dfrac{0.0792}{0.30}=0.264$

Hence, the conditional probability that a randomly selected family owns a dog given that it owns a cat = 0.264

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3 years ago

Solve for x: m(fx+a)=z+g

Inga [223]

X= -a/f = z/mf + g/mf
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3 years ago

Read 2 more answers

If you earned $2000 in 10 mins how much would you earn in an hour?

MrRissso [65]

find out how much you earn per minute 2000/10=200

in an hour there are 60 minutes.

multiply the amount earned in a minute by the amount of minutes.

200*60=12000

So you earn $12,000 per hour

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3 years ago

How many milliequivalents of sodium chloride are contained with 3 L of normal saline?

AVprozaik [17]

Answer:

466mEq

Step-by-step explanation:

First, we need to know the concentration of NaCl in a normal saline solution, this is by definition 0.9%, meaning we have 0.9g of NaCl per 100ml of solution, we want to know how much NaCl we have in 3L (3000ml):

$3000ml*\frac{0.9g}{100ml}=27g=27000mg$

So, we have 27000mg in 3L of normal saline solution.

Now, acording to our milliequivalent (mEq) equation ( $mEq=\frac{mg}{pE}$ ) where pE is de molecular mass of NaCl divided by their charges, in this case 1: