Do-Now Evaluate the expression when x = –3. –5 ANSWER 1. 3x

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Do-Now Evaluate the expression when x = –3. –5 ANSWER 1. 3x + 4 12 –15 4. The amount a that a taxi service charges is given by a = 1.5m where m is the number of miles. Find a when m is 7. ANSWER $10.50

Find the intercepts of the graph of an equation Lesson 4.3 Find the intercepts of the graph of an equation Find the x-intercept and the y-intercept of the graph of 2x + 7y = 28. SOLUTION To find the x-intercept, substitute 0 for y and solve for x. 2x + 7y = 28 Write original equation. 2x + 7(0) = 28 Substitute 0 for y. x = = 14 28 2 Solve for x. To find the y-intercept, substitute 0 for x and solve for y. ANSWER The x-intercept is 14. The y-intercept is 4.

GUIDED PRACTICE 1. 3x + 2y = 6 2. 4x – 2y = 10 3. – 3x + 5y = – 15 Find the x-intercept and the y-intercept of the graph of the equations. 1. 3x + 2y = 6 2. 4x – 2y = 10 3. – 3x + 5y = – 15

Use intercepts to graph an equation EXAMPLE Use intercepts to graph an equation Graph the equation x + 2y = 4. SOLUTION STEP 1 Find the intercepts. x + 2y = 4 x + 2y = 4 x + 2(0) = 4 0 + 2y = 4 x =  x-intercept 4 y =  y-intercept 2 STEP 2 Plot points. The x-intercept is 4, so plot the point (4, 0). The y- intercept is 2, so plot the point (0, 2). Draw a line through the points.