AlgebraGRAPHINGGraphingEquationsAlgebraic equations involving two unknowns can readily be shown on a graph. Figure 7 showsa plot of the equation x + y = 5. The equation is solved for corresponding sets of values of xand y that satisfy the equation. Each of these points is plotted and the points connected. Thegraph of x + y = 5 is a straight line.The x-intercept of a line on a graph is defined as the value of the x-coordinate when theFigure 7 Plot of x + y = 5y-coordinate is zero. It is the value of x where the graph intercepts the x-axis. The y-interceptof a graph is defined as the value of the y-coordinate when the x-coordinate is zero. It is thevalue of y where the graph intercepts the y-axis. Thus, the x-intercept of the graph of x + y =5 is +5. For a linear equation in the general form ax + by = c, the x-intercept and y-interceptcan also be given in general form.Any algebraic equation involving two unknowns of any function relating two physical quantitiescan be plotted on a Cartesian coordinate graph. Linear equations or linear functions plot asstraight lines on Cartesian coordinate graphs. For example, x + y = 5 and f(x) = 3x + 9 plot asstraight lines. Higher order equations or functions, such as quadratic equations or functions andexponential equations, can be plotted on Cartesian coordinate graphs. Figure 8 shows the shapeof the graph of a typical quadratic equation or function. This shape is called a parabola. Figure9 shows the shape of the graph of a typical exponential equation or function.Rev. 0 Page 81 MA-02

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