Direct and Inverse Variation Review

1
Direct and Inverse Variation Review

• MATH 7

2
What am I?direct, inverse, or both

• As one variable increases, the other variable
  decreases.
• The graph is always a straight line.
• 3. The equation is

3
What am I?direct, inverse, or both

• As one variable decreases, the other variable
  decreases.
• The equation is
• The graph is never a straight line.

4
What am I?direct, inverse, or both

• It is a proportional relationship between 2
  variables.
• As one variable increases, the other variable
  increases.

5
What am I?direct, inverse, or both

• When x and y are multiplied, the result is a
  constant (k).
• 10. When y is divided by x, the result is a
  constant (k).

6
Solve each problem

• X varies inversely with y. If x 10 when y 2,
  what is the value of y when x 4?
• 2. X varies inversely with y. If x 7 when y
  12, what is the value of y when x 4?

7
Solve each problem

• y varies directly with x. If y 16 and x 2,
  what is the value of y when x 5?
• 4. y varies directly with x. If y 36 and x
  4, what is the value of y when x 5?

8
Solve each problem

• Alex has 28 to spend on cds and dvds. If he
  buys 4 cds, he will be able to buy 7 dvds. How
  many cds would he be able to buy if he only
  bought 14 dvds?

9
Find the constant

• X and y vary inversely
• y2.5 and x4
• X and y vary directly
• y25 and x2