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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 59

Complete the square and write the equation in standard form. Then give the center and radius of each circle and graph the equation. x² - 2x + y² – 15 = 0

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Start with the given equation: \(x^{2} - 2x + y^{2} - 15 = 0\).
Group the \(x\) terms and the \(y\) terms together, and move the constant to the other side: \(x^{2} - 2x + y^{2} = 15\).
Complete the square for the \(x\) terms. Take half of the coefficient of \(x\) (which is \(-2\)), square it, and add it to both sides: half of \(-2\) is \(-1\), and \((-1)^{2} = 1\). So add \(1\) to both sides: \(x^{2} - 2x + 1 + y^{2} = 15 + 1\).
Rewrite the perfect square trinomial as a binomial squared: \((x - 1)^{2} + y^{2} = 16\).
Identify the center and radius of the circle from the standard form \((x - h)^{2} + (y - k)^{2} = r^{2}\). Here, the center is \((1, 0)\) and the radius is \(\,\sqrt{16}\).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Completing the Square

Completing the square is a method used to rewrite quadratic expressions in the form (x - h)² = k by adding and subtracting a constant. This technique helps transform the equation into a form that reveals geometric properties, such as the center and radius of a circle.
추천 영상:
06:24
Solving Quadratic Equations by Completing the Square

Standard Form of a Circle

The standard form of a circle's equation is (x - h)² + (y - k)² = r², where (h, k) is the center and r is the radius. Writing the equation in this form makes it easy to identify these key features and understand the circle's position and size.
추천 영상:
5:18
Circles in Standard Form

Graphing Circles

Graphing a circle involves plotting its center (h, k) and using the radius r to mark points at a distance r in all directions. This visual representation helps in understanding the circle's location and size on the coordinate plane.
추천 영상:
5:18
Circles in Standard Form