What is the density of the oak board

Please help with #12 im confused<br> that is the key but i dont get it

Svetllana [295]

Given Equation

$\boxed{ \tt \: (8 \sqrt{3} - 2 \sqrt{2} )(8 \sqrt{3} + 2 \sqrt{2})}$

Step by step expansion:

$\dashrightarrow \sf \: (8 \sqrt{3} - 2 \sqrt{2} )(8 \sqrt{3} + 2 \sqrt{2})$

$\\ \\$

$\dashrightarrow \sf \: (8 \sqrt{3})^{2} - (2 \sqrt{2} {)}^{2}$

Reason:

(a + b)(a - b) = a²- b²

$\\ \\$

$\dashrightarrow \sf \: (8 {}^{2} \times { \sqrt{3} }^{2} )- (2 \sqrt{2} {)}^{2}$

$\\ \\$

$\dashrightarrow \sf \: (64 \times 3 ) - (2 \sqrt{2} {)}^{2}$

$\\ \\$

$\dashrightarrow \sf \: (64 \times 3 ) - (2 {}^{2} \times \sqrt{2} {}^{2} {)}$

$\\ \\$

$\dashrightarrow \sf \: 192- 8$

$\\ \\$

$\dashrightarrow \sf \: 184$

$\\ \\$

~BrainlyVIP ♡

4 0

2 years ago

Read 2 more answers

A paint company mixes it's paint with water to create more paint per gallon. They currently have ten gallon jugs which contain 1

Karo-lina-s [1.5K]

<h3>Answer: 1.25 gallons</h3>

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Explanation:

They currently have ten gallon jugs that contain 10% water, so this means 0.10*10 = 1 gallon of the jug is water and the other 10-1 = 9 gallons is paint. This is assuming the cans are just paint and water.

The ratio of paint to water is 90:10 which reduces to 9:1

Often it helps to reduce as much as possible, but it's actually more handy in this case to keep it at 90:10 so you can see the two parts add back up to 100%

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Let x be the amount of water we add. This amount is in gallons.

We start off with 1 gallon of water and it bumps up to 1+x gallons of water.

The overall amount of 10 gallons also bumps up to 10+x gallons.

We want a ratio of 80:20 this time, so we want 20 parts water and 80 parts paint. In other words, we want 20/(20+80) = 20/100 = 20% water

Divide (1+x) over (10+x) to get (1+x)/(10+x). This represents the fraction of water. We want this fraction to be equal to 0.20, which is the 20% water amount. It is also equal to 20/100.

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(1+x)/(10+x) = 20/100

100(1+x) = 20(10+x) ... cross multiply

100+100x = 200+20x ... distribute

100x-20x = 200-100

80x = 100

x = 100/80 ... divide both sides by 80

x = 1.25

You need to add 1.25 gallons of water

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If you add 1.25 gallons of water, then,

amount of water = 1+x = 1+1.25 = 2.25

amount of paint&water = 10+x = 10+1.25 = 11.25

So you'll have 2.25 gallons of water out of 11.25 gallons of water&paint mix

2.25/11.25 = 0.2 = 20% water

This confirms our answer.

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Extra info:

1.25 gallons = 1 gallon + 1/4 gallon

1.25 gallons = 1 gallon + 1 quart

This is because 1 gallon = 4 quarts, so 1 quart = 1/4 gallon.

5 0

3 years ago

Solve the system of equations by graphing, elimination or

vladimir1956 [14]

Answer:

Solve the system of equations by graphing, elimination or

subod

Step-by-step explanation:

8 0

2 years ago

A. Evaluate the polynomial

sdas [7]

Answer:

a) y = x³− 5x² + 6x + 0.55 at x = 1.37.

Use 3-digit arithmetic with chopping. Evaluate the percent relative round-off error.

-1.183%

b. Express y as y = ((x − 5)x + 6)x + 0.55 (this is the same equation). Use again 3-digit arithmetic with chopping. Evaluate the percent relative round-off error and compare with part (a). Make the conclusion about which form of the polynomial is superior.

-0.161%

Comparing part a and b together, part b is more superior because the percent(%) error is smaller when compared to part a

Step-by-step explanation:

a) y = x³− 5x² + 6x + 0.55 at x = 1.37.

Use 3-digit arithmetic with chopping. Evaluate the percent relative round-off error.

Let's evaluate before applying the 3 digit arithmetic chopping rule

y = 1.37³ - 5 × 1.37² + 6 × 1.37 + 0.55

y = 1.956853

Let evaluate each components of the polynomial one by one

Note that: 3-digit arithmetic chopping means to approximate chop off or remove number after the 3 significant figures.

y = x³− 5x² + 6x + 0.55 at x = 1.37.

x³ = 1.37³ = 2.571353

≈ 2.57

x² = 1.37² = 1.8769

≈ 1.88

5x² = 1.87 × 5

= 9.35

x = 1.37

6x = 1.37 × 6

6x = 8.22

Evaluating the polynomial

y = 2.57 - 9.38 + 8.22 + 0.55

y = 1.98

The percent relative round-off error =

1.956853 - 1.98/1.956853 × 100

= -1.183%

b. Express y as y = ((x − 5)x + 6)x + 0.55 (this is the same equation). Use again 3-digit arithmetic with chopping. Evaluate the percent relative round-off error and compare with part (a). Make the conclusion about which form of the polynomial is superior.

y = ((x − 5)x + 6)x + 0.55

Evaluating with the 3 digit chop off rule is applied

= ((1.37 - 5)1.37 + 6)1.37 + 0.55

=( 1.8769 - 6.85) + 6) 1.37 + 0.55

= (- 4.9731 + 6 )1.37 + 0.55

= 1.0269 × 1.37 + 0.55

= 1.406853

= 1.956853.

≈ 1.96

Note in: evaluating before applying the 3 digit arithmetic chopping rule

y = 1.37³ - 5 × 1.37² + 6 × 1.37 + 0.55

y = 1.956853

The percent relative round-off error

1.956853 - 1.96/1.956853 × 100

= -0.161%

Comparing part a and b together, part b is more superior because the percent(%) error is smaller when compared to part a

3 0

3 years ago

I will give brainliest!!!!!!!!!!!!!<br> please answer all the questions and no links! :)

Scilla [17]

Answer:

1. a

2. b (i think)

3. b

4. a

5. d

im not sure bout all this but h ope it helps you

3 0

3 years ago