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Evaluate each expression. 1. 6 a + 3 for a = 2 2. –2 x – 5 for x = 3 3. x + 2 for x = 16 4. 0.2 x + 2 for x = 15 Solve each equation for y . 5. y – 5 = 4 x 6. y + 2 x = 7 7. 2 y + 6 = –8 x. 1 4. Slope-Intercept Form. ALGEBRA 1 LESSON 6-2.
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Evaluate each expression. 1. 6a + 3 for a = 2 2. –2x – 5 for x = 3 3.x + 2 for x = 16 4. 0.2x + 2 for x = 15 Solve each equation for y. 5.y – 5 = 4x6.y + 2x = 7 7. 2y + 6 = –8x 1 4 Slope-Intercept Form ALGEBRA 1 LESSON 6-2 (For help, go to Lessons 1-6 and 2-6.) 8-4
1 4 1 4 2y y Slope-Intercept Form ALGEBRA 1 LESSON 6-2 Solutions 1. 6a + 3 for a = 2: 6(2) + 3 = 12 + 3 = 15 2. –2x – 5 for x = 3: –2(3) – 5 = –6 – 5 = –11 3.x + 2 for x = 16: (16) + 2 = 4 + 2 = 6 4. 0.2x + 2 for x = 15: 0.2(15) + 2 = 3 + 2 = 5 5.y – 5 = 4x6.y + 2x = 7 y – 5 + 5 = 4x + 5 y + 2x – 2x = 7 – 2x y = 4x + 5 y = –2x + 7 7. 2y + 6 = –8x 2y + 6 – 6 = –8x – 6 2y = –8x – 6 = y = –4x – 3 –8x – 6 2 8-4
What are the slope and y-intercept of y = 2x – 3? Use the Slope-Intercept form. mx + b = 2x – 3 = Slope-Intercept Form ALGEBRA 1 LESSON 6-2 The slope is 2; the y-intercept is –3. 8-4
2 5 Use the slope-intercept form. Substitute for m and4 for b. y = mx + b 2 5 2 5 y = x + 4 Slope-Intercept Form ALGEBRA 1 LESSON 6-2 Write an equation of the line with slope and y-intercept 4. 8-4
Write an equation for the line. Step 1 Find the slope. Two points on the line are (0, 1) and (3, –1). –1 – 1 3– 0 slope = 2 3 = – y = mx + b Step 2 Write an equation in slope– intercept form. The y-intercept is 1. 2 3 y = – x + 1 Substitute – for mand 1 for b. 2 3 Slope-Intercept Form ALGEBRA 1 LESSON 6-2 8-4
Graph y = x – 2. Step 2 The slope is . Use slope to plot a second point. Step 3 Draw a line through the two points. Step 1 The y-intercept is –2. So plot a point at (0,–2). 1 3 Slope-Intercept Form ALGEBRA 1 LESSON 6-2 1 3 8-4
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 equations. Step 1 Identify the slope and y-intercept. t = 300 + 0.15s t = 0.15s + 300 Rewrite the equation in slope intercept form. slopey-intercept Slope-Intercept Form ALGEBRA 1 LESSON 6-2 8-4
15 100 Step 3 Draw a line through the points. Slope-Intercept Form ALGEBRA 1 LESSON 6-2 (continued) Step 2 Plot two points. First plot a point at the y-intercept. Then use the slope to plot a second point. The slope is 0.15, which equals . Plot a second point 15 units above and 100 units to theright of the y-intercept. 8-4
Find the slope and y-intercept of each equation. 1.y = x – 3 2.y = –2x Write an equation of a line with the given slope and y-intercept. 3.m = – , b = –4 4.m = 0.5, b = 1 1 2 3 4 y = x – 3 3 4 m = ; b = –3 3 5 3 5 y = – x – 4 Slope-Intercept Form ALGEBRA 1 LESSON 6-2 5. Write an equation for the line. m = –2; b = 0 6. Graph y = –x + 3. y = 0.5x + 1 8-4