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Lorico [155]
3 years ago
11

What is the value of (7 + 2i)(3 - i)?

Mathematics
1 answer:
Harrizon [31]3 years ago
7 0
There are two ways to work this out: normal variables or using "imaginary" numbers.

Normal variables:
(7+2i)(3-i)\\(7*3)+[7*(-i)]+(3*2i)+[2i*(-i)]\\21-7i+6i-2i^{2}\\\\21-i-2i^{2}

Imaginary numbers:
Using the result from earlier:
21-i-2i^{2}
Now since i = \sqrt{-1}, then the expression becomes:
21-i-2i^{2}\\21-i-2(\sqrt{-1})^{2}\\21-i+(-2)(-1)\\21-i+2\\\\23-i
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What is the first step in solving quadratic equations by finding square roots? a. give the positive and negative answer c. squar
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Answer:

C: isolate the x squared by using inverse operations

Step-by-step explanation:

This method of solving quadratic equation is used when there is only x² term and no x term. Thus;

For example, we have a quadratic equation;

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To solve this by square root method, the first step we have to take is to isolate the x² term by inverse operation which is by addition of 1 to both sides to get rid of the -1 on the left side so that x² can be isolated.

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3 years ago
Number of gallons of gas. Miles driven 0 0 2 62 4 124 10 310 How many gallons are used when the car has been driven 18 miles
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558 gallons are used when the car has been driven 18 miles.

<u>Step-by-step explanation:</u>

<u>From the given data, it can be determined that :</u>

  • The number of gallons for 2 miles = 62 gallons
  • The number of gallons for 4 miles = 124 gallons
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Let, the number of gallons for 18 miles = 'x' gallons

<u>To find x :</u>

compare the given data with the unknown data,

62 gallons / 2 miles = x gallons / 18 miles

keep x alone on one side,

x = (62×18) / 2

x = 31×18

x = 558 gallons

Therefore, 558 gallons are used to drive 18 miles.

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The answer to "12x-(4y+7z) for x=9 y= 4 and z = 2" is 78.

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