1. Review for Quiz
Activities 12

2. 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

3. 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.

4. Question #3 Write an equation of a line that represents this dataX 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

5. 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)

6. 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)

7. 4x + 6y = 20
-4x x
6y = -4x + 20
y = -2/3x + 10/3
Question #6
3x + y = 4
-3x x
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

8. 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 = note: Since the “A” value is negative, multiply the equation by -1
2x – 3y = 30

9. 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 x
9y = -2x – 36
y = -2/9 x - 4

10. Question #9
Graph the equation x = Graph the equation y = -2

11. 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

12. 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).