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vichka [17]
3 years ago
13

Simplify the expression (3 - 4i)(1 + 5i) - (2 - i). Show your work

Mathematics
1 answer:
jek_recluse [69]3 years ago
3 0

Answer: 12i + 21

Step-by-step explanation:

You want to apply foil to the first two terms.

  1. 3 x 1 = 3
  2. 5i x 3 = 15i
  3. -4i x 1 = -4i
  4. -4i x 5i = -20i^2

You get 3 + 11i - 20i^2. i is equal to the square root of -1, so when you square it, you will get -1. Then do -1 x -20 to get +20

So far you have (11i + 23) - (-i + 2).

  1. 11i + i = 12i
  2. 23 - 2 = 21

Im 99% sure the answer is 12i + 21

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Answer:

The interval from the sample of size 400 will be approximately <u>One -half as wide</u> as the interval from the sample of size 100

Step-by-step explanation:

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=>   E_1 \sqrt{400} =  E_2 \sqrt{100}

=>  E_1 =  \frac{\sqrt{100} }{\sqrt{400} } E_2

=>  E_1 =  \frac{1}{2 } E_2

So From this we see that  the confidence interval for a sample size of 400 will be half that with a sample size of 100

   

     

   

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