Problem 87 - Introductory Algebra for College Students

Question

In which quadrant is \(\left(-\frac{3}{2}, 15\right)\) located? (Section 3.1, Example 1)

Step-by-Step Solution

Answer

The point \(\left(-\frac{3}{2}, 15\right)\) is located in Quadrant II.

Step 1: Identify the coordinates of the point

The given point has the coordinates \(\left(-\frac{3}{2}, 15\right)\). This means it has a x-coordinate of \(-\frac{3}{2}\) and a y-coordinate of \(15\)

Step 2: Apply knowledge of quadrant organization

In Cartesian plane, Quadrant I contains all points with positive x and y coordinates. Quadrant II contains points where x is negative and y is positive. Quadrant III contains points where both x and y are negative. Quadrant IV contains points where x is positive and y is negative.

Step 3: Determine the quadrant

For the point \(\left(-\frac{3}{2}, 15\right)\), the x-coordinate is negative and the y-coordinate is positive. This means the point belongs to Quadrant II.

Key Concepts

Coordinate System

Understanding the coordinate system is fundamental in mathematics, especially when dealing with the Cartesian plane. The Cartesian plane is a two-dimensional surface that is defined by two perpendicular lines that intersect at a fixed point called the origin. These lines are referred to as axes, with the horizontal axis known as the x-axis and the vertical axis called the y-axis.

The coordinate system allows us to pinpoint the exact location of a point on the plane by using an ordered pair of numbers (x, y), known as coordinates. The x-coordinate tells us how far to move right (positive) or left (negative) from the origin, while the y-coordinate indicates the movement up (positive) or down (negative).

To effectively utilize the coordinate system, it's important to familiarize oneself with its layout, as this serves as the foundation for graphing equations, performing quadrant analysis, and plotting points in various quadrants.

Quadrant Analysis

Quadrant analysis is a key aspect of working within the Cartesian plane. The plane is divided into four sections called quadrants, which are numbered counterclockwise starting from the upper right quadrant.

• Quadrant I (QI) is where both x and y coordinates are positive.
• Quadrant II (QII) contains points with a negative x-coordinate and a positive y-coordinate.
• Quadrant III (QIII) includes points where both coordinates are negative.
• Quadrant IV (QIV) is characterized by a positive x-coordinate and a negative y-coordinate.

By analyzing the sign of a point's coordinates, we can easily determine in which quadrant the point lies. This quadrant identification is crucial for understanding the relationship between algebraic equations and their geometric interpretations on the plane.

Plotting Points in Quadrants

Plotting points in the correct quadrant on a Cartesian plane is a common task in mathematics that requires precision and understanding of the coordinate system. To plot a point, you start at the origin and move horizontally to the x-coordinate value, then vertically to the y-coordinate value.

For instance, considering the point \(\left(-\frac{3}{2}, 15\right)\), we would move left from the origin due to the negative x-coordinate \(\left(-\frac{3}{2}\right)\) and then move upward because of the positive y-coordinate \(\left(15\right)\). Following these steps leads us to Quadrant II, where the point \(\left(-\frac{3}{2}, 15\right)\) is located, as determined in the textbook solution. This process reinforces the understanding of how to navigate the coordinate plane and solidifies the skills needed to graphically represent mathematical concepts.