Presentation on theme: "Section 6-2: Slope-Intercept Form of a Linear Equation SPI 22C: select the graph that represents a given linear function expressed in slope-intercept form."— Presentation transcript:
Section 6-2: Slope-Intercept Form of a Linear Equation SPI 22C: select the graph that represents a given linear function expressed in slope-intercept form Objective: Graph and write linear equations using slope-intercept form 1. Slope-Intercept form: y = mx + b 2. Standard Form: Ax + By = C 3. Point-Slope form: y – y 1 = m (x – x 1 ) 3 Different Forms of a Linear Equation Linear equation: an equation whose graph is a line the variable will have an exponent of 1 y- Intercept: point where line crosses the y-axis
0 Identify parts in Slope-Intercept Form X Y y = mx + b f(x)slopey-intercept Graph y = 3 x + 2 4 1. Plot y-intercept 2. From known point, plot slope. (Rise over run) 3. Connect the 2 points with a line.
0 Practice: Slope Intercept Form X Y Graph y = - 1 x – 2 2 1. Plot y-intercept 2. From known point, plot slope. 3. Connect the 2 points with a line.
If you know the slope of a line and the y-intercept, you can write the equation of a line. (0, 4) Write a Linear Equation in Slope-Intercept Form 1. Find the slope of the line. (0, 4) (8, 1) (0, 4) (8, 1) 2. Find the y-intercept. (0, 4) 3. Substitute values into slope-intercept form of an equation.
Write an equation of the line with slope and with a y-intercept of 4. 2525 y = mx + b Write the slope-intercept equation y = 2/5x + 4 Substitute in know values Write a Linear Equation in Slope-Intercept Form
Step 3 Write an equation in slope–intercept form, using the given information Write an equation for the line. Step 1 Find the slope. Write the slope formula: m = y 2 – y 1 x 2 – x 1 (0, 1) m = 1 – (-1) = 2 0 – 3 -3 y = mx + b y = - 2/3x + 1 Write a Linear Equation from a Graph Step 2 Find the y-intercept. Substitute in values
The base pay for a used car salesperson is $300 per week. The salesperson also earns 15% commission on sales made. The equation t = 300 + 0.15s relates total earnings (t) to sales (s). Graph the equation. Real-world and Slope-Intercept 1. What is the y-intercept? t = 300 + 0.15s (0, 300) 2. What is the slope? 3. Plot the y-intercept first. Plot slope, starting at y-intercept.