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Key Terms Chapter 04: Graphs

  • Page ID
    101921
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    Boundary Line
    The line with equation \(Ax+By=C\) that separates the region where \(Ax+By>C\) from the region where \(Ax+By<C\).
    Geoboard
    A geoboard is a board with a grid of pegs on it.
    Graph of a Linear Equation
    The graph of a linear equation \(Ax+By=C\) is a straight line. Every point on the line is a solution of the equation. Every solution of this equation is a point on this line.
    Horizontal Line
    A horizontal line is the graph of an equation of the form \(y=b\). The line passes through the y-axis at \((0,b)\).
    Intercepts of a Line
    The points where a line crosses the \(x\)-axis and the \(y\)-axis are called the intercepts of the line.
    Linear Equation
    A linear equation is of the form \(Ax+By=C\), where \(A\) and \(B\) are not both zero, is called a linear equation in two variables.
    Linear Inequality
    An inequality that can be written in one of the following forms:

    \[Ax+By>C \qquad Ax+By≥C \qquad Ax+By<C \qquad Ax+By≤C\]

    where \(A\) and \(B\) are not both zero.
    Negative Slope
    A negative slope of a line goes down as you read from left to right.
    Ordered Pair
    An ordered pair \((x,y)\) gives the coordinates of a point in a rectangular coordinate system.
    Origin
    The point \((0,0)\) is called the origin. It is the point where the \(x\)-axis and \(y\)-axis intersect.
    Parallel Lines
    Lines in the same plane that do not intersect.
    Perpendicular Lines
    Lines in the same plane that form a right angle.
    Point–Slope Form
    The point–slope form of an equation of a line with slope \(m\) and containing the point \((x_1,y_1)\) is \(y−y_1=m(x−x_1)\).
    Positive Slope
    A positive slope of a line goes up as you read from left to right.
    Quadrant
    The \(x\)-axis and the \(y\)-axis divide a plane into four regions, called quadrants.
    Rectangular Coordinate System
    A grid system is used in algebra to show a relationship between two variables; also called the \(xy\)-plane or the ‘coordinate plane’.
    Rise
    The rise of a line is its vertical change.
    Run
    The run of a line is its horizontal change.
    Slope Formula
    The slope of the line between two points \((x_1,y_1)\) and \((x_2,y_2)\) is \(m=\frac{y_2−y_1}{x_2−x_1}\).
    Slope of a Line
    The slope of a line is \(m=\frac{\text{rise}}{\text{run}}\). The rise measures the vertical change and the run measures the horizontal change.
    Slope-Intercept Form of an Equation of a Line
    The slope–intercept form of an equation of a line with slope \(m\) and \(y\)-intercept, /((0,b)\) is, \(y=mx+b\).
    Solution of a Linear Inequality
    An ordered pair \((x,y)\) is a solution to a linear inequality the inequality is true when we substitute the values of \(x\) and \(y\).
    Vertical Line
    A vertical line is the graph of an equation of the form \(x=a\). The line passes through the \(x\)-axis at \((a,0)\).
    X-intercept
    The point \((a,0)\) where the line crosses the \(x\)-axis; the \(x\)-intercept occurs when \(y\) is zero.
    X-coordinate
    The first number in an ordered pair \((x,y)\).
    Y-coordinate
    The second number in an ordered pair \((x,y)\).
    ​​​​​​​Y-intercept
    The point \((0,b)\) where the line crosses the \(y\)-axis; the \(y\)-intercept occurs when \(x\) is zero.
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