1. Is this a direct variation?
Course 2
Identifying DV
Is this a direct variation? x y -2 -4 -1 1 2 4 x y 1 6 2 12 3 18 4 24 x y 3 6 5 10 7 14 4 8 12

2. Is this a direct variation?
Course 2
Identifying DV
Is this a direct variation?

3. QUESTION How are direct variation problems solved using the equation?
Course 2
DV Problems
Insert Lesson Title Here
QUESTION
How are direct variation problems solved using the equation?

4. To solve problems: DV Problems
If there is more than one set of data, make a t-table with the given information.
Using the equation y = kx or the ratio k = y/x, substitute the known values.
3. Solve for k.
Course 2

5. DV Problems Substitute the k value into direct variation equation.
Solve for the value of y.
Course 2

6. Find an equation of direct variation.
Course 2
DV Problems
Example:
Find an equation of direct variation.
y is when x is 4

7. Insert Lesson Title Here
Course 2
DV Problems
Insert Lesson Title Here
Example:
x varies directly with y. If y = 8 when x = 12, what is the value of y when x = 15? x y 12 8 15 ?

8. QUESTION How are direct variation problems solved using proportion?
Course 2
DV Problems
Insert Lesson Title Here
QUESTION
How are direct variation problems solved using proportion?

9. DV Problems 1. Substitute given values into the proportion
2. Solve for the value of y using cross product.
Course 2

10. Course 2
DV Problems
Example:
x varies directly with y. If y = when x = -2.5, what is the value of y when x = -8?

11. Insert Lesson Title Here
Course 2
DV Problems
Insert Lesson Title Here
Practice Problems
Find an equation of the direct variation when y is -64, x is 4.
Find an equation of the direct variation when y is 6.3, x is 0.7
Find an equation of the direct variation when y is ½ , x is ¼ .
y = -16x
y = 9x
y = 2x

12. Insert Lesson Title Here
Course 2
DV Problems
Insert Lesson Title Here
Practice Problems
x varies directly with y. If x = 5 when y = 4.45, what is the value of y when x = 7.12?
x varies directly with y. If x = -2 when y = -3/2, what is the value of y when x = -4?
x varies directly with y. If x = 5 when y = 4.5, what is the value of y when x = 1.5?
y =
y = -3
y = 1.35

13. Is this a direct variation?
Course 2
Identifying DV
Is this a direct variation? x y -2 -4 -1 1 2 4 x y 1 6 2 12 3 18 4 24 x y 3 6 5 10 7 14 4 8 12

14. Is this a direct variation?
Course 2
Identifying DV
Is this a direct variation?