### All GRE Subject Test: Math Resources

## Example Questions

### Example Question #1 : Circles

What is the equation of a circle with center at and a radius of ?

**Possible Answers:**

**Correct answer:**

Step 1: Recall the general equation for a circle (if the vertex is not at :

, where center=

Step 2: Recall the shift of the graph..

If the value of is positive, it will be shown as a negative shift in the equation.

If the value of is negative, it will be shown as a positive shift in the equation.

If the value of is positive, it will be shown as a negative shift in the equation.

If the value of is negative, it will be shown as a positive shift in the equation.

Step 3: Look at the center given in the problem and find the rule(s) in step 2 that will apply:

Center=, ,

Step 4: Plug in into the equation of a circle:

Simplify:

### Example Question #2 : Circles

What is the vertex of the equation of a circle:

**Possible Answers:**

**Correct answer:**

Step 1: There are no numbers next to and , so their is no movement of the vertex..

Step 2: Recall the vertex of a circle that does not move...

The vertex of this circle is .

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### All GRE Subject Test: Math Resources

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