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irina [24]
2 years ago
11

Long rationalise surds questions pls help​

Mathematics
1 answer:
Katena32 [7]2 years ago
3 0

Answer:

Noah mistakenly added 25 and 7 in denominator instead of subtracting in the third step.

Step-by-step explanation:

Noah had to rationalize the denominator of \frac{32}{5-\sqrt{7}}

According to him,

\frac{32}{5-\sqrt{7} = \frac{32(5+\sqrt{7}{(5-\sqrt{7})(5+\sqrt{7}

Solving the nominator and denominator

= \frac{160-32\sqrt{7}}{25+5\sqrt{7}-5\sqrt{7}-7}

Noah did correctly till this point.

In the next step he add 25 and 7 in the denominator, whereas, it should be subtracted.

Hence,

Noah mistakenly added 25 and 7 in denominator instead of subtracting in the third step.

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Three boxes of supplies have an average (arithmetic mean) weight of 7 kilograms and a median weight of 9 kilograms. What is the
GuDViN [60]

Answer:

3

Step-by-step explanation:

A) 1

(B) 2

(C) 3

(D) 4

(E) 5

Mean is a measure of central tendency. It is the average of a set of numbers. It is determined by adding the numbers together and dividing it by the total number

Mean = sum of numbers / number of observation

sum of numbers = 3 x 7 = 21

Median is the number that is at the center or middle of a set of obervations

x +  9+ y = 21

x= lowest number

y = highest number

x + y = 21 - 9

x + y = 12

If x = 1 y = 11

if x = 2 y = 10

if x = 3 y = 9

if x = 4 y = 8

the first 3 are plausible and the median would still be 9 if x = 4, median would be 8

3 0
2 years ago
What is the sum of the 12th square number and the 6th square number?​
aleksklad [387]

Answer:

180

Step-by-step explanation:

The 12 th square number is

12² = 12 × 12 = 144

The 6 th square number is

6² = 6 × 6 = 36

Thus

sum = 144 + 36 = 180

5 0
3 years ago
A DVD that originally cost $30 is on sale for 10 percent off. Complete the steps to solve the problem
Wittaler [7]

Answer:

3$

Step-by-step explanation:

the discount is 27 so that leaves 3 dollars if

30-27=3 ^^

8 0
2 years ago
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The following lists the joint probabilities associated with smoking and lung disease among 60-to-65 year-old men. Has Lung Disea
Anna71 [15]

Answer:

4.11% probability that he has lung disease given that he does not smoke

Step-by-step explanation:

We use the conditional probability formula to solve this question. It is

P(B|A) = \frac{P(A \cap B)}{P(A)}

In which

P(B|A) is the probability of event B happening, given that A happened.

P(A \cap B) is the probability of both A and B happening.

P(A) is the probability of A happening.

In this question:

Event A: Does not smoke

Event B: Lung disease

Lung Disease/Nonsmoker 0.03

This means that P(A \cap B) = 0.03

Lung Disease/Nonsmoker 0.03

No Lung Disease/Nonsmoker 0.7

This means that P(A) = 0.03 + 0.7 = 0.73

What is the probability of the following event: He has lung disease given that he does not smoke?

P(B|A) = \frac{0.03}{0.73} = 0.0411

4.11% probability that he has lung disease given that he does not smoke

5 0
3 years ago
3x2 + 5x - 7(x2 + 4)
goldenfox [79]

Answer:

-4x^2+5x-28

Step-by-step explanation:

Expand -7(x^2 +4) = 3x^2+5x-7x^2-28

Simplify 3x^2+5x-7x^2-28 = -4x^2+5x-28

5 0
3 years ago
Read 2 more answers
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