Answer: Choice D
15(cos85° + i sin85°)
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Explanation:
Let's say we had these two general complex numbers, which are in polar form.

We can abbreviate them into the shorthand form

The notation "cis" stands for "cosine i sine".
Now that we have those complex numbers set up, multiplying them is as simple as saying this:

We do two basic things:
- Multiply the r values out front
- Add the theta values inside the the cis function
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With all that in mind, let's tackle the problem your teacher gave you.
The given complex numbers

abbreviate into

then those multiply to

which is why choice D is the final answer.
Answer:{0,2}
Step-by-step explanation:
Substitute 4x in for the y
2x^2-4x=0
Factor out GCF 2x
2x(x-2)=0
Set each factor = 0 and solve
2x=0 x=0 x-2=0 x=2
She asked her friends, which does not represent a random sample.
She tried to show cause and effect without doing an experiment (which includes simple random sample, control group, treatment, etc).
So the answer is she did not use a random sample, and tried to show cause and effect with an observational study.