All categories

2 years ago

For all real numbers a and b, 2a • b = a2 + b2 Is this true or false? Explain why it false or true.

Mathematics

1 answer:

Andru [333]2 years ago

3 0

Answer:

It's false.... correct is a2+2ab+b2

Step-by-step explanation:

This cannot be factored anymore although. when we try to substitute a with 5 and b with 2, the answer in the right hand side of the equation is -9.

That's why it's false.

You might be interested in

O is the centre of the circle, EF is a tangent, angle BCE=28 degrees, angle ACD=31 degrees.

Yuki888 [10]

Answer:

a. 28˚

b. 76˚

c. 104˚

d. 56˚

Step-by-step explanation

a. because angle between tangent and chord is equal to the angle(s) in alternate segment.

b. because angles in triangles add up to 180˚, 180-28=152 and because isosceles triangle, 152/2=76˚

c. because angles in triangles add up to 180˚ and opposite angles in a cyclic quadrilateral add up to 180˚, 31+76=107, 180-107=73, 73-28=45, angles in triangle so 180-(31+45)=104˚

d. 28*2=56˚ because angles at circumference are half angles at centre

4 0

2 years ago

What value of x makes the equation -4x – (-3 − 5x) = -3(2x − 8) true?

mezya [45]

Answer:hrhdhf end b

Step-by-step explanation:

Rndjdbajrcb

5 0

1 year ago

Bob, Bill, and Joe measured their heights. They figured out that the height of Bob is equal to b cm and he makes up 8/9 of the h

andrezito [222]

Answer:

Joe is 12 times taller than Bob

No the answer not rely on the meaning of b

Step-by-step explanation:

* Lets explain how the solve the problem

- The height of Bob is equal to b cm

- The height of Bob is 8/9 of the height of Bill

- Because 8/9 is less than one , then Bob is shorter than Bill

- The height of Bill makes up 3/32 of the height of Joe

* Lets write these information by mathematics relation

∵ The height of Bob is b

∵ The height of Bob is 8/9 height of Bill

∴ b = 8/9 the height of Bill

- Multiply both sides by 9

∴ 9 b = 8 the height of Bill

- Divide both sides by 8

∴ 9/8 b = the height of Bill

∴ The height of Bill is 9/8 b

∵ The height of Bill is 3/32 the height of Joe

∴ 9/8 b = 3/32 the height of Joe

- Multiply both sides by 32

∴ 36 b = 3 the height of Joe

- Divide both sides by 3

∴ 12 b = the height of Joe

∴ The height of Joe is 12 b

∵ b is the height of Bob

∴ The height of Joe is 12 times the height of Bob

∴ Joe is 12 times taller than Bob

- NO, the answer doesn't depend on b because the ratio between the

heights of Joe and Bob doesn't change by the change of b

8 0

2 years ago

Rocky Mountain National Park is a popular park for outdoor recreation activities in Colorado. According to U.S. National Park Se

Ugo [173]

Answer:

a) 0.6628 = 66.28% probability that at least 85 visitors had a recorded entry through the Beaver Meadows park entrance

b) 0.5141 = 51.41% probability that at least 80 but less than 90 visitors had a recorded entry through the Beaver Meadows park entrance

c) 0.5596 = 55.96% probability that fewer than 12 visitors had a recorded entry through the Grand Lake park entrance.

d) 0.9978 = 99.78% probability that more than 55 visitors have no recorded point of entry

Step-by-step explanation:

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

In this problem, we have that:

$n = 175$

(a) What is the probability that at least 85 visitors had a recorded entry through the Beaver Meadows park entrance?

46.7% of visitors to Rocky Mountain National Park in 2018 entered through the Beaver Meadows. This means that $p = 0.467$ . So

$\mu = E(X) = np = 175*0.467 = 81.725$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{175*0.467*0.533} = 6.6$

This probability, using continuity correction, is $P(X \geq 85 - 0.5) = P(X \geq 84.5)$ , which is 1 subtracted by the pvalue of Z when X = 84.5. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{84.5 - 81.725}{6.6}$

$Z = 0.42$

$Z = 0.42$ has a pvalue of 0.6628.

66.28% probability that at least 85 visitors had a recorded entry through the Beaver Meadows park entrance.

(b) What is the probability that at least 80 but less than 90 visitors had a recorded entry through the Beaver Meadows park entrance?

Using continuity correction, this is $P(80 - 0.5 \leq X < 90 - 0.5) = P(79.5 \leq X \leq 89.5)$ , which is the pvalue of Z when X = 89.5 subtracted by the pvalue of Z when X = 79.5. So

X = 89.5

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{89.5 - 81.725}{6.6}$

$Z = 1.18$

$Z = 1.18$ has a pvalue of 0.8810.

X = 79.5

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{79.5 - 81.725}{6.6}$

$Z = -0.34$

$Z = -0.34$ has a pvalue of 0.3669.

0.8810 - 0.3669 = 0.5141

51.41% probability that at least 80 but less than 90 visitors had a recorded entry through the Beaver Meadows park entrance

(c) What is the probability that fewer than 12 visitors had a recorded entry through the Grand Lake park entrance?

6.3% of visitors entered through the Grand Lake park entrance, which means that $p = 0.063$

$\mu = E(X) = np = 175*0.063 = 11.025$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{175*0.063*0.937} = 3.2141$

This probability, using continuity correction, is $P(X < 12 - 0.5) = P(X < 11.5)$ , which is the pvalue of Z when X = 11.5. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{11.5 - 11.025}{3.2141}$

$Z = 0.15$

$Z = 0.15$ has a pvalue of 0.5596.

55.96% probability that fewer than 12 visitors had a recorded entry through the Grand Lake park entrance.

(d) What is the probability that more than 55 visitors have no recorded point of entry?

22.7% of visitors had no recorded point of entry to the park. This means that $p = 0.227$

$\mu = E(X) = np = 175*0.227 = 39.725$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{175*0.227*0.773} = 5.54$

Using continuity correction, this probability is $P(X \leq 55 + 0.5) = P(X \leq 55.5)$ , which is the pvalue of Z when X = 55.5. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{55.5 - 39.725}{5.54}$

$Z = 2.85$

$Z = 2.85$ has a pvalue of 0.9978

0.9978 = 99.78% probability that more than 55 visitors have no recorded point of entry

8 0

2 years ago

Arthur took out a 20 year loan for $60,000 at an APR of 4.4% compounded monthly. Approximately how munch would save if he paid i

Eduardwww [97]

Monthly payments, P = {R/12*A}/{1- (1+R/12)^-12n}

Where R = APR = 4.4% = 0.044, A = Amount borrowed = $60,000, n = Time the loan will be repaid

For 20 years, n = 20 years
P1 = {0.044/12*60000}/{1- (1+0.044/12)^-12*20} = $376.36

Total amount to be paid in 20 years, A1 = 376.36*20*12 = $90,326.30

For 3 years early, n = 17 year
P2 = {0.044/12*60,000}/{1-(1+0.044/12)^-12*17} = $418.22

Total amount to be paid in 17 years, A2 = 418.22*17*12 = $85,316.98

The saving when the loan is paid off 3 year early = A1-A2 = 90,326.30 - 85,316.98 = $5,009.32

Therefore, the approximate amount of savings is A. $4,516.32. This value is lower than the one calculated since the time of repaying the loan does not change. After 17 years, the borrower only clears the remaining amount of the principle amount.

8 0

2 years ago

Read 2 more answers