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3 years ago

Solve the system of equations using subtraction. 2x-4y= -12 2x+y=8 plz help

Mathematics

1 answer:

m_a_m_a [10]3 years ago

3 0

Answer:

x=2, y= 4

Step-by-step explanation:

Equation 1 is 2x-4y = -12

Equation 2 is 2x+y = 8

Subtracting the two equations gives -4y-y = -12-8 (The 2x and the other 2x cancel each other out).

Simplifying we get -5y = -20 and y =4

Substituting y =4 into original equation back we get 2x -4(4) =-12

This equals 2x -16 =-12 and 2x = 4 and x =2

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4 years ago

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3 years ago

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3 years ago

If $9,000 is invested in an account for 15 years. Find the value of the investment at the end of 15 years if the interest is:

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6 0

2 years ago

Studies show that most children need an average of ten hours per sleep, while most adults only require an average of seven hours

motikmotik

Solution:

Part A

The line of best fit for a five year children is given as

$Y =\frac {-x}{8} +\frac{113}{8},$

When children is 5 , years old, average that children will sleep each night

can be calculated by , putting, x=5 in above equation

$Y=\frac {-5}{8} +\frac{113}{8}\\\\ Y=\frac{108}{8}\\\\ Y=13.5$

Average sleep of 5 year old children , given by line of best fit= 13.5 hours

But it is given that, Average that a five year old children sleep= 10 hours

Difference between calculated and Actual = 13.5 - 10 = 3.5 hours, which is not so large,for a five year old children, but a large value, showing that it is not a reasonable estimate.

Part B

The line of best fit for a 20 year old is given as

$Y =\frac {-x}{8} +\frac{113}{8},$

When adult who is 20 , years old, average that adult will sleep each night

can be calculated by , putting, x=20 in above equation

$Y=\frac {-20}{8} +\frac{113}{8}\\\\ Y=\frac{93}{8}\\\\ Y=11.625$

Average sleep of 20 year old adult , given by line of best fit= 11.625 hours

But it is given that, Average that a 20 year old adult sleeps= 7 hours

Difference between calculated and Actual = 11.625 - 7 = 4.625 hours, which is quite large, for an adult, showing that it is not a reasonable estimate.

6 0

4 years ago