While attempting to multiply the expression (2-5i)(5+2i) a student made a mistake.

Mathematics

2 answers:

julsineya [31]3 years ago

4 0

Answer:

The left side of the equation is ignored

i is treated as -1, which it is not, it is instead the square root of negative 1.

To solve it properly we get:

(2 - 5i)(5 + 2i)

= 10 + 4i - 25i - 10i²

= 10 + 21i + 10

= 20 - 21i

Nata [24]3 years ago

4 0

Answer:

The error is that, the student replaced i with -1 which is wrong as i = √-1

And he has replaced i^2 with 1 while i^2 = -1

Step-by-step explanation:

Given two numbers that are being multiplied are:

(2-5i)(5+2i)

We will solve the question to get the right result so that the error can be detected.

So, multiplying both

$= 2(5+2i)-5i(5+2i)\\=10+4i-25i-10i^2\\=10-21i-10(-1)\ \ \ as\ i^2 = -1\\=10-21i+10$

The error is that, the student replaced i with -1 which is wrong as i = √-1

And he has replaced i^2 with 1 while i^2 = -1

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A recent Harris Poll survey of 1010 U.S. adults selected at random showed that 627 consider the occupation of firefighter to hav

Semmy [17]

Answer: 0.62

Step-by-step explanation:

Given : A recent Harris Poll survey of 1010 U.S. adults selected at random showed that 627 consider the occupation of firefighter to have very great prestige.

i.e. The sample size of U.S. adults : n= 1010

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Now , the probability that a U.S adult selected at random thinks the occupation of firefighters has very great prestige will be :

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3 years ago

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kondaur [170]

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