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kow [346]
3 years ago
8

Solve the system of equations by using substitution. x+8y=-2 x-3y=20

Mathematics
1 answer:
zysi [14]3 years ago
4 0

Answer:

(14, -2)

Step-by-step explanation:

To solve by using substitution, begin by solving for a variable in the first equation. Let's solve for x:

x+8y=-2\\x=-2-8y

Now we know what <em>x</em> equals. Let's substitute this into the second equation:

x-3y=20\\(-2-8y)-3y=20

We can then simplify:

-2-8y-3y=20 Given equation

-2-11y=20 Combine y terms

-11y=22 Add 2

y=-2 Divide by -11

So, we now know the value of y = -2.

To find the value of X, we can substitute the value of Y into one of the equations. Let's use the first one:

x+8y=-2

x+8(-2)=-2 Substitute for y

x-16=-2 Distribute 8

x=14 Add 16

So, we now know the value of x = 14.

Therefore, we know a solution to the system of equations is (14, -2).

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A motor vehicle has a maximum efficiency of 39 mpg at a cruising speed of 40 mph. The efficiency drops at a rate of 0.1 mpg/mph
svp [43]

Answer:

38 mpg

Step-by-step explanation:

Initial efficiency = 39 mpg

Initial speed = 40 mph

Final speed = 50 mph

The efficiency drop  between 40 mph and 50 mph is given by:

E_d = 0.1 \frac{mpg}{mph}*\Delta V

The total efficiency drop from 40 to 50 mph is:

E_d = 0.1 \frac{mpg}{mph}*(50-40)mph\\E_d = 1\ mpg

Therefore, the efficiency at 50 mph is:

E_{50} = E_{40} -E_d\\E_{50} = 39 -1\\E_{50} = 38\ mpg

5 0
3 years ago
Is the answer to -8.8-3.4 positive or negative? I know. It is 12.2 but I don't know if it's -12.2 or +12.2
Marat540 [252]
It is negative.

When you subtract a negative a positive number from a negative number, the result is positive. The equation can be rewritten as -8.8-(+3.4).
6 0
3 years ago
The temperature of coffee served at a restaurant is normally distributed with an average temperature of 160 degrees Fahrenheit a
posledela

Answer:

The 20th percentile of coffee temperature is 155.4532 degrees Fahrenheit.  

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 160 degrees

Standard Deviation, σ = 5.4 degrees

We are given that the distribution of temperature of coffee is a bell shaped distribution that is a normal distribution.

Formula:

z_{score} = \displaystyle\frac{x-\mu}{\sigma}

We have to find the value of x such that the probability is 0.2

P( X < x) = P( z < \displaystyle\frac{x - 160}{5.4})=0.2  

Calculation the value from standard normal z table, we have,  

\displaystyle\frac{x - 160}{5.4} = -0.842\\\\x = 155.4532  

Thus,

P_{20}=155.4532

The 20th percentile of coffee temperature is 155.4532 degrees Fahrenheit.

7 0
3 years ago
A farmer has 24 bushels of apples and can harvest 22 bushels of apples each day?
sweet-ann [11.9K]

Answer:

................ I don"t know sorry I hate you

5 0
2 years ago
Two bike rental companies have different pricing systems. Company a charges a flat fee of $4 plus $2 per mile. Company b does no
EastWind [94]

Answer:it will the take 5 mitutes

Step-by-step explanation:

Let x represent the distance at which both companies charge the same amount.

Let y represent the cost of x miles when using company A.

Let z represent the cost of x miles when using company B.

Company A charges a flat fee of $4 plus $2 per mile. It means that

y = 4 + 2x

Company b does not charge a flat fee but charges $2.80 per mile driven. This means that

z = 2.8x

To determine the distance before both plans will be be the same, we would equate both equations. It becomes.

4 + 2x = 2.8x

2.8x - 2x = 4

0.8x = 4

x = 4/0.8 = 5

3 0
3 years ago
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