How to multiply complex numbers - PSAT Math

Card 0 of 11

Question

Which of the following is equal to ?

Answer

, so 56 is a multiple of 4. raised to the power of any multiple of 4 is equal to 1, so

.

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Question

Multiply:

Answer

This is the product of a complex number and its complex conjugate. They can be multiplied using the pattern

with

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Question

Which of the following is equal to ?

Answer

By the power of a product property,

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Question

Which of the following is equal to ?

Answer

The first step to solving this problem is distributing the exponent:

Next, we need simplify the complex portion.

Thus, our final answer is .

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Question

Simplify:

Answer

Use the FOIL method that states to multiply the Firsts, Outter, Inner, Lasts. Also remember that :

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Question

What is the eighth power of ?

Answer

raised to the power of any multiple of 4 is equal to 1, so the above expresion is equal to

This is not among the given choices.

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Question

What is the third power of ?

Answer

You are being asked to evaluate

You can use the cube of a binomial pattern with :

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Question

What is the fourth power of ?

Answer

can be calculated by squaring , then squaring the result, using the square of a binomial pattern as follows:

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Question

Multiply by its complex conjugate. What is the product?

Answer

The product of any complex number and its complex conjugate is the real number , so all that is needed here is to evaluate the expression:

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Question

What is the eighth power of ?

Answer

First, square using the square of a binomial pattern as follows:

Raising this number to the fourth power yields the correct response:

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Question

What is the ninth power of ?

Answer

To raise a negative number to an odd power, take the absolute value of the base to that power and give its opposite:

To raise to a power, divide the power by 4 and raise to the remainder. Since

,

Therefore,

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