Exploring Direct Variation Concepts

What is the equation that represents direct variation?

• y = K - X

• y = K + X

• y = K/X

• y = KX

What do we call the constant K in the equation y = KX?

• Direct constant

• Slope constant

• Constant of proportionality

• Constant of variation

In a graph showing direct variation, where must the line pass through?

• The origin

• The y-axis

• Any point on the graph

• The x-axis

If a line does not pass through the origin, does it show direct variation?

• Sometimes

• Yes

• No

• Depends on the slope

In the first example, why do x and y not show direct variation?

• The line is not straight

• The line does not pass through the origin

• The values of x and y are not proportional

• The equation is not in the form y = KX

In the second graph example, why do x and y show direct variation?

• The line is straight

• The equation is in the form y = KX

• The line passes through the origin

• The values of x and y are proportional

What is the first step in solving for y in the equation y = 2X - 1?

• Subtract 1 from both sides

• Add 1 to both sides

• Multiply both sides by 2

• Divide both sides by 2

Does the equation y = 2X - 1 show direct variation?

• No

• Yes

• Sometimes

• Depends on the value of X

What is the reciprocal of 1/2?

• 1

• 2

• 1/4

• 1/2

Does the equation y = 2X show direct variation?

• Yes

• No

• Sometimes

• Depends on the value of X