# Finding the Center and Radius of the Circle 4x^2 - 24x + 4y^2 - 21y + 21 = 0 | Summary and Q&A

8.7K views
October 12, 2014
by
The Math Sorcerer
Finding the Center and Radius of the Circle 4x^2 - 24x + 4y^2 - 21y + 21 = 0

## TL;DR

This content provides a step-by-step guide on finding the center and radius of an equation by completing the square.

## Key Insights

• 🧑‍🏭 Grouping and factoring out common factors is the first step in finding the center and radius of an equation.
• 🍉 Completing the square involves adjusting the squared term and constant term to maintain balance in the equation.
• 🍉 Accurate addition of squared terms and constant adjustments are crucial to obtain the correct center and radius.
• 🍉 The center coordinates are determined by the opposite values inside the parentheses, and the radius is the square root of the constant term.
• ❎ Division of coefficients by 2 and squaring the result helps in setting up the equation for completing the square.
• 🥺 Incorrect addition of squared terms can lead to significant errors in finding the center and radius.
• ❣️ The center is denoted by (x, y), and the radius provides information about the distance from the center to any point on the equation.

## Transcript

so we have to find the center and radius solution so start by grouping all the x terms and all the y terms and subtracting the 21 so we get 4x squared minus 24x plus 4y squared minus 28y equals negative 21. now we'll factor out a 4 from here and factor out a 4 from here so we get 4 let's see x squared minus 6x right because 4 times minus 6 is minus... Read More

### Q: What are the initial steps to find the center and radius of an equation?

The initial steps involve grouping the x and y terms, subtracting the constant term from both sides, factoring out common factors, and setting up the equation for completing the square.

### Q: How do you determine the coefficients for completing the square?

To determine the coefficients, divide the coefficient of x or y by 2 and square the result. Add this value to the equation after the squared term and adjust the constant term accordingly.

### Q: Why is it essential to correctly add the squared term on both sides of the equation?

Adding the squared term correctly ensures that the equation remains balanced and reflects the process of completing the square accurately. Mistakes in this step can lead to incorrect results for the center and radius.

### Q: How do you calculate the center and radius based on the completed square form?

The center is given by the opposite of the values inside the parentheses (x, y), and the radius is the square root of the constant term outside the parentheses.

## Summary & Key Takeaways

• The content explains the process of finding the center and radius of an equation by grouping all the x and y terms, factoring out common factors, and completing the square.

• It emphasizes the importance of correctly adding the squared terms and adjusting the constant term on both sides of the equation.

• The final result gives the center coordinates (x, y) and the radius of the equation.