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2 years ago

Rewrite the subtraction expression as an addition expression, and then simplify (find the sum). -2 -3

Mathematics

1 answer:

Vinvika [58]2 years ago

6 0

Answer: -2 + (-3) = -5

Step-by-step explanation:

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100 points! simplify write as a product compute

Rom4ik [11]

Answer:

a) $\sqrt{61 - 24 \sqrt{5} } = - 4 + 3 \sqrt{5}$

b) $( \sqrt{ ( {c}^{2} - 1) ({b}^{2} - 1) } - {2 \sqrt{bc} }) (\sqrt{ ( {c}^{2} - 1) ({b}^{2} - 1) } + {2 \sqrt{bc} } )$

c) $\frac{ \sqrt{9 - 4 \sqrt{5} } }{2 - \sqrt{5} } = - 1$

Step-by-step explanation:

We want to simplify

$\sqrt{61 - 24 \sqrt{5} }$

Let :

$\sqrt{61 - 24 \sqrt{5} } = a - b \sqrt{5}$

Square both sides of the equation:

$(\sqrt{61 - 24 \sqrt{5} } )^{2} = ({a - b \sqrt{5} })^{2}$

Expand the RHS;

$61 - 24 \sqrt{5} = {a}^{2} - 2ab \sqrt{5} + 5 {b}^{2}$

Compare coefficients on both sides:

${a}^{2} + 5 {b}^{2} = 61 - - - (1)$

$- 24 = - 2ab \\ ab = 12 \\ b = \frac{12}{b} - - -( 2)$

Solve the equations simultaneously,

$\frac{144}{ {b}^{2} } + 5 {b}^{2} = 61$

$5 {b}^{4} - 61 {b}^{2} + 144 = 0$

Solve the quadratic equation in b²

${b}^{2} = 9 \: or \: {b}^{2} = \frac{16}{5}$

This implies that:

$b = \pm3 \: or \: b = \pm \frac{4 \sqrt{5} }{5}$

When b=-3,

$a = - 4$

Therefore

$\sqrt{61 - 24 \sqrt{5} } = - 4 + 3 \sqrt{5}$

We want to rewrite as a product:

${b}^{2} {c}^{2} - 4bc - {b}^{2} - {c}^{2} + 1$

as a product:

We rearrange to get:

${b}^{2} {c}^{2} - {b}^{2} - {c}^{2} + 1- 4bc$

We factor to get:

${b}^{2} ( {c}^{2} - 1) - ({c}^{2} - 1)- 4bc$

Factor again to get;

$( {c}^{2} - 1) ({b}^{2} - 1)- 4bc$

We rewrite as difference of two squares:

$(\sqrt{( {c}^{2} - 1) ({b}^{2} - 1) })^{2} - ( {2 \sqrt{bc} })^{2}$

We factor the difference of square further to get;

$( \sqrt{ ( {c}^{2} - 1) ({b}^{2} - 1) } - {2 \sqrt{bc} }) (\sqrt{ ( {c}^{2} - 1) ({b}^{2} - 1) } + {2 \sqrt{bc} } )$

c) We want to compute:

$\frac{ \sqrt{9 - 4 \sqrt{5} } }{2 - \sqrt{5} }$

Let the numerator,

$\sqrt{9 - 4 \sqrt{5} } = a - b \sqrt{5}$

Square both sides of the equation;

$9 - 4 \sqrt{5} = {a}^{2} - 2ab \sqrt{5} + 5 {b}^{2}$

Compare coefficients in both equations;

${a}^{2} + 5 {b}^{2} = 9 - - - (1)$

and

$- 2ab = - 4 \\ ab = 2 \\ a = \frac{2}{b} - - - - (2)$

Put equation (2) in (1) and solve;

$\frac{4}{ {b}^{2} } + 5 {b}^{2} = 9$

$5 {b}^{4} - 9 {b}^{2} + 4 = 0$

$b = \pm1$

When b=-1, a=-2

This means that:

$\sqrt{9 - 4 \sqrt{5} } = - 2 + \sqrt{5}$

This implies that:

$\frac{ \sqrt{9 - 4 \sqrt{5} } }{2 - \sqrt{5} } = \frac{ - 2 + \sqrt{5} }{2 - \sqrt{5} } = \frac{ - (2 - \sqrt{5)} }{2 - \sqrt{5} } = - 1$

3 0

3 years ago

Read 2 more answers

Answer this if you can 37÷264

docker41 [41]

.1401515152 is not the answer

6 0

3 years ago

Read 2 more answers

If 1 gram = 100 centigrams and 1 centigram = 10 milligrams, how many

Alja [10]

Answer:

1,420 milligrams

Step-by-step explanation:

We know there are 100 centigrams in 1 gram, and there are 10 milligrams in a centigrams. That would mean there are 1,000 milligrams in 1 gram (100 * 10 = 1000).

As a result, all you need to do is multiply 1.42 by 1000 to get the amount of milligrams.

1.42 * 1000

Alternatively, to make 1.42 a whole number first, multiply by 100, then add a zero. (That's the other 10!)

(1.42 * 100) * 10

142 * 10

There are 1,420 milligrams in 1.42 grams.

3 0

2 years ago

Read 2 more answers

The area of a parallelogram is 5 cm Squared. explain why you can find the area without knowing the dimensions of the parallelogr

Ivan

Answer:

because a square always has the same length on each side so yo just see what number multiplies to that.

Step-by-step explanation:

6 0

3 years ago

The Wall Street Journal reported that the median salary for middle-level manager jobs was approximately $85,000 (The Wall Street

vredina [299]

Answer:

Median = $80,000 ; Mean = $84,000 ; Q1 = 67,000 ; Q3 = 106,000

Step-by-step explanation:

Given the data :

108 83 106 73 53 85 80 63 67 75 124 55 93 118 77

Reorderd data :

53, 55, 63, 67, 73, 75, 77, 80, 83, 85, 93, 106, 108, 118, 124

The median salary:

1/2(n+1)th term

Sample size, n = 15

1/2 (15 + 1)th term

1/2(16)th term

8th term = 80

Median is $80,000

Median reported by Wall Street Journal approximately $85000

The obtained and reported values are close

The mean annual salary :

ΣX / n = 1260 / 15 = 84

Mean annual salary = $84,000

Mean is the average of all earnings combined, median is the mid value of he data.

First and third quartile :

Q1 = 1/4(n+1)th term

Q1 = 1/4(16)th term

Q1 = 4th term = 67

Third quartile:.

Q3 = 3/4(n+1)th term

Q3 = 3/4(16)th term

Q3 = 12th term = 106

3 0

3 years ago