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1.1 Integers and Rational Numbers

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www.ck12.org Chapter 11. More on Linear Functions11.2 Writing Linear Equations in St<strong>and</strong>ard FormAs the past few lessons of this chapter have shown, there are several ways to write a linear equation. This lessonintroduces another method: st<strong>and</strong>ard form. You have already seen examples of st<strong>and</strong>ard form equations in aprevious lesson. For example, here are some equations written in st<strong>and</strong>ard form.0.75(h) + 1.25(b) = 307x − 3y = 212x + 3y = −6The st<strong>and</strong>ard form of a linear equation has the form Ax + By = C, where A,B, <strong>and</strong> C are integers <strong>and</strong> A <strong>and</strong> B arenot both zero.Example 1: Rewrite y − 5 = 3(x − 2) in st<strong>and</strong>ard form.Solution: Use the Distributive Property to simplify the right side of the equationy − 5 = 3x − 6Rewrite this equation so the variables x <strong>and</strong> y are on the same side of the equation.y − 5 + 6 = 3x − 6 + 6y − y + 1 = 3x − y1 = 3x − y, where A=3, B=-1, <strong>and</strong> C=1.Example 2: Rewrite 5x − 7 = y in st<strong>and</strong>ard form.Solution: Rewrite this equation so the variables x <strong>and</strong> y are on the same side of the equation.5x − 7 + 7 = y + 75x − y = y − y + 75x − y = 7,where A=5, B=-1, <strong>and</strong> C=7.Finding Slope <strong>and</strong> Intercept of a St<strong>and</strong>ard Form EquationSlope-intercept form of a linear equation contains the slope of the equation explicitly, but the st<strong>and</strong>ard form doesnot. Since the slope is such an important feature of a line, it is useful to figure out how you would find the slope ifyou were given the equation of the line in st<strong>and</strong>ard form.Begin with st<strong>and</strong>ard form: Ax + By = C.If you rewrite this equation in slope-intercept form, it becomes217

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