Basic Function Rules

The output is eight more than the input

• y = x + 8
• x + 8
• x = y + 8
• y = x - 8

The output is four times the input.

• y = x/4
• 4x
• y = 4x
• y = x +4

The output is four more than twice the input.

• y = +4 2x
• y = 4x + 2
• y = 4x + x/2
• y = 2x + 4

The mathcounts team is taking a field trip.  The cost for each person is $22 to go into the place and the parking will cost $15 for the day. 

• c = 15p + 22
• c = 22p + 15
• p = 15c + 22
• p = 22c + 15

The output is eight less than three times the input.

• y = 3x - 8
• 3x - 8
• y = 8 - 3x
• 8 - 3x

The output is 4 less than half the input.

• y = 2x - 4
• y = 4 - 2x
• y = x/2 - 4
• y = 4 - x/2

The cost of admission for a student is 4 less than the cost of admission for an adult.

• x - 4
• 4 - x
• y = 4 - x
• y = x - 4

The output is one-third the input.

• 1/3x
• 3x
• y = 1/3x
• y = 3x

The number of multiple-choice questions on a test is ten times the number of open-ended questions.  Write a function that describes the relationship.

• y = 10x
• x = 10y
• y = 10 + x
• x = 10 + y

The output is thirteen more than four times the input.

• y = x/4 + 13
• y = 4x + 13
• y = 4x - 13
• y = 4/x - 13