Review for Quiz Activities 12

Use the slope-intercept form Question #1 Write an equation of a line that has a slope of -5 and y-intercept (0, ¼ ) Use the slope-intercept form y = mx + b y = -5x + ¼

Question #2 If Michael has $300 and has been saving $40 every month. He now has $650. Write an equation in slope intercept form. How many months has Michael been saving? $300 is the initial fee (y-intercept) and $40 is the rate of change (slope). y = 40x + 300 650 = 40x +300 X = 8.75 months.

Question #3 Write an equation of a line that represents this data X y -5 -2 5 -4 Find the slope. Change in y -2 Change in x 5 The y-intercept is (0, -2) Equation y = -2/5x - 2

Question #4 Write an equation of the line in point-slope form. The slope is rise over run, which is 3. One point from the line is (1, 4). y – 4 = 3(x – 1)

Question #5 The slope of a line is 7 and the point (2, - 4) lies on the line. Write an equation of the line in point-slope form. y + 4 = 7(x – 2)

4x + 6y = 20 -4x -4x 6y = -4x + 20 6 6 y = -2/3x + 10/3 Question #6 3x + y = 4 -3x -3x y = -3x + 4 Write an equation in slope-intercept from of the line with the same slope as the line described by 4x + 6y = 20 and the same y-intercept as the line described by 3x + y = 4. y = -2/3x + 4

Write an equation of the line 3y = 2(x – 15) written in standard form. Question #7 Write an equation of the line 3y = 2(x – 15) written in standard form. 3y = 2(x – 15) goal : Ax + By = C 3y = 2x – 30 -2x -2x -2x + 3y = -30 note: Since the “A” value is negative, multiply the equation by -1 2x – 3y = 30

y-intercept : set x=0 2(0) + 9y= -36 0 + 9y = -36 9y = -36 y = -4 (0, -4) x-intercept : set y=0 2x + 9(0) = -36 2x + 0 = -36 2x = -36 x = -18 (-18, 0) Question #8 Determine the x-intercept, y-intercept, and slope of the line described by 2x + 9y = -36. To find the slope, change the equation to slope-intercept form. 2x + 9y = -36 -2x -2x 9y = -2x – 36 9 9 y = -2/9 x - 4

Question #9 Graph the equation x = 4 Graph the equation y = -2

Is 2x + 4y = -8 parallel to y = ½ x + 5 Question #10 Is 2x + 4y = -8 parallel to y = ½ x + 5 Change 2x + 4y = -8 to slope-intercept form: y = -1/2x -2 Answer: No, because they have different slopes

Step 1: Find the slope = 13/4 Step 2: use either point to write the an equation with the same slope since the lines are parallel y = 13/4x -3 or y – 10 = 13/4(x – 4) Question #11 Write an equation of a line that is parallel to the line containing the points (0, -3) and (4, 10).