2.1.4 Writing Linear Functions
Key Objectives • Use slope-intercept form and point-slope form to write linear functions. • Find the slope of a line given two or more points. • Write linear functions to solve problems. • Write equations of parallel and perpendicular lines. Key Terms • A linear equation is in slope-intercept form when it is written in the form y = mx + b , where m represents slope and b represents the y -intercept. • The point-slope form of an equation of a line with slope m passing through ( x 1 , y 1 ) is y − y 1 = m ( x − x 1 ). • Parallel lines are lines in the same plane that have the same slope, and therefore never intersect. • Perpendicular lines are lines that have slopes that are opposite reciprocals of one another, and therefore intersect at 90° angles. Example 1 Writing the Slope-Intercept Form of the Equation of a Line Recall that the slope-intercept form equation of a line is y = mx + b , where m is the slope of the line and b is the y -intercept.
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