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BARSIC [14]
3 years ago
13

Multiply the following complex numbers:(7-3i)(8 + 4i)​

Mathematics
1 answer:
mel-nik [20]3 years ago
3 0

Answer:

A

Step-by-step explanation:

Noting that i² = - 1

Given

(7 - 3i)(8 + 4i) ← expand factors using FOIL

= 56 + 28i - 24i - 12i²

= 56 + 4i - 12(- 1)

= 56 + 4i + 12

= 68 + 4i → A

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frez [133]

Answer:

41

Step-by-step explanation:

3 0
3 years ago
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Insurance companies are interested in knowing the population percent of drivers who always buckle up before riding in a car. The
lys-0071 [83]

Answer:

The 85% confidence interval for the population proportion that claim to always buckle up is (0.7877, 0.8441).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of \pi, and a confidence level of 1-\alpha, we have the following confidence interval of proportions.

\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}

In which

z is the zscore that has a pvalue of 1 - \frac{\alpha}{2}.

They randomly survey 391 drivers and find that 319 claim to always buckle up.

This means that n = 391, \pi = \frac{319}{391} = 0.8159

85% confidence level

So \alpha = 0.15, z is the value of Z that has a pvalue of 1 - \frac{0.15}{2} = 0.925, so Z = 1.44.

The lower limit of this interval is:

\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.8159 - 1.44\sqrt{\frac{0.8159*0.1841}{391}} = 0.7877

The upper limit of this interval is:

\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.8159 + 1.44\sqrt{\frac{0.8159*0.1841}{391}} = 0.8441

The 85% confidence interval for the population proportion that claim to always buckle up is (0.7877, 0.8441).

8 0
3 years ago
A grocery store sells a bag of 6 oranges for $4.80. If Austin spent $8.00 on oranges, how many did he buy
boyakko [2]

Answer:

10 oranges

Step-by-step explanation:

6 oranges is sold for $4.80

1 orange= 4.80/6

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= 8/0.8

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3 years ago
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Illusion [34]

Step-by-step explanation:

if he buys 7 pounds, it will cost 7×5 = $35

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so,

c >= $35

3 0
3 years ago
5/3 - x + 1/3 <br> answer?
ANEK [815]

Answer:

x = 5

Step-by-step explanation:

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