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3 years ago

Solve using linear combination. 8x+14y=4 -6x-7y+-10

Mathematics

1 answer:

emmasim [6.3K]3 years ago

4 0

It's best to write the two equations as a vertical column:

8x+14y=4

-6x-7y = -10

Note that if we multiply the 2nd equation by 2, we get -12x - 14y = -20. The reason for wanting this version of the 2nd equation is that its -14y cancels the +14y in the first equation:

-12x - 14y = -20

8x+14y=4

Combine these equations, column by column. We get -4x = -16, which results in x = 4. Now find y by subbing 4 for x in either given equation. If we use the first equation, we get 8(4) + 14y = 4, or 32 + 14y = 4, or 14y = -28. Then y = -2.

The solution to this system of linear equations is thus (4,-2).

Check this result by substitution of these coordinates into -6(4) - 7y = -20:

-24 - 7(-2) = -10. Is this true or not?

-24 + 14 = -10 is true. Thus, (4,-2) is the desired solution.

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3 years ago

Trigonometry:

Trava [24]

A. The approximate height of the building is 100 m

B. We can use the arc length formula to obtain an approximation of BC since angle A is small.

The approximate height of the building is 100 m

To find the approximate height of the building, we consider the diagram.

From the diagram, we have that using trigonometry,

tanA = BC/AB

Now

A = 0.05 radians,
BC = height of building and
AB = 2 km = 2000 m

<h3 /><h3>Finding the value of BC</h3>

So, making BC subject of the formua, we have

BC = ABtanA

Substituting the values of the variables into the equation, we have

BC = ABtanA

BC =2000tan0.05

BC = 2000 × 0.05

BC = 100 m

So, the approximate height of the building is 100 m

We can use the arc length formula to obtain an approximation of BC since angle A is small.

<h3 /><h3>Arc Length Formula</h3>

We know that the arc length formula L = rФ where

r = radius and
Ф = angle in radians

<h3 /><h3>The approximate height</h3>

Now BC = ABtanA

We know that Ф ≅ tanФ when Ф is small.

<h3 /><h3>The comparison</h3>

So, BC = AB × A which is the arc length formula with

L = BC,
r = AB and
Ф = A

So, we can use the arc length formula to obtain an approximation of BC since angle A is small.

Learn more about approximate height of building here:

brainly.com/question/3144976

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2 years ago

A drawer contains 3 black socks, 3 white socks, 2 red socks, and 1 purple sock. A red sock is pulled at random from the drawer,

arsen [322]

The answer is d. since the sock with a hole was returned, the probability of getting a black sock is out of 3 out of 9 because there are 3 black socks and 9 socks total. hope this helps!