### All GRE Subject Test: Math Resources

## Example Questions

### Example Question #1 : Operations On Complex Numbers

Expand and Simplify:

**Possible Answers:**

**Correct answer:**

Step 1: We will multiply the two complex conjugates: and .

Step 2: Replace with .

Simplify:

Step 3: Multiply the result of the complex conjugates to the other parentheses,.

The final answer after the product of all three binomials is

### Example Question #2 : Operations On Complex Numbers

Expand: .

**Possible Answers:**

**Correct answer:**

Quick Way:

Step 1: Expand .

.

Remember:

Step 2:

By this equivalence, I can just raise the answer of to the power .

. Replace ..

Final answer:

Long Way:

### Example Question #1 : Operations On Complex Numbers

Multiply:

**Possible Answers:**

**Correct answer:**

Step 1: FOIL:

Recall, FOIL means to multiply the first terms in both binomials together, the outer terms together, the inner terms together, and finally, the last terms together.

Step 2: Simplify:

Step 3: Recall: . Replace and simplify.

### Example Question #4 : Operations On Complex Numbers

**Possible Answers:**

**Correct answer:**

When adding imaginary numbers, simply add the real parts and the imaginary parts.

### Example Question #1 : Operations On Complex Numbers

**Possible Answers:**

**Correct answer:**

### Example Question #1 : Operations On Complex Numbers

What is the value of ?

**Possible Answers:**

None of the other answers

**Correct answer:**

Distribute and Multiply:

Simplify all terms...

### Example Question #7 : Operations On Complex Numbers

What is the value: ?

**Possible Answers:**

**Correct answer:**

Step 1: Recall the cycle of imaginary numbers to a random power .

If , then

If , then

If , then

If , then

If , then

and so on....

The cycle repeats every terms.

For **ANY** number , you can break down that term into smaller elementary powers of i.

Step 2: Distribute the to all terms in the parentheses:

.

Step 3: Recall the rules for exponents:

Step 4: Use the rules to rewrite the expression in Step 2:

Step 5: Simplify the results in Step 4. Use the rules in Step 1.:

Step 6: Write the answer in form, where is the real part and is the imaginary part:

We get

### Example Question #8 : Operations On Complex Numbers

**Possible Answers:**

**Correct answer:**

When adding complex numbers, we add the real numbers and add the imaginary numbers.

### Example Question #9 : Operations On Complex Numbers

**Possible Answers:**

**Correct answer:**

In order to subtract complex numbers, we must first distribute the negative sign to the second complex number.

### Example Question #10 : Operations On Complex Numbers

**Possible Answers:**

**Correct answer:**

First we must distribute