Functions Word Problems

Word Problems - Linear Functions

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Slope-Intercept Form: y=mx + b

• m is the slope or rate of change

• b is the y-intercept, which is our starting point

• Rates can be described with phrases "each, for each, per..."

• Starting points sometimes use phrases like "initial, flat rate, one-time fee, ..."

Multiple Choice

It costs $4 per month to join a dance club plus a $30 startup fee.

In this situation, which number is the "b" value?

• $4

• $30

• $7.50

Multiple Choice

An airplane 30,000 fee above the ground begins to descend at a rate of 2,000 feet per minute. Write an equation in slope-intercept form to model the situation.

• y = -30,000x + 2,000

• y = 30,000x - 2,000

• y = -2,000x + 30,000

• y = 2,000x - 30,000

Open Ended

How can you tell if a value given is the y-intercept? How can you tell if a value is the rate of change (slope)?

Standard Form: Ax + By = C

• "A" can be a rate for x

• "B" can be a rate for y

• C is the total

Multiple Choice

A 100-point test has x questions worth 2-points each and y questions worth 4 points each.

Which equation describes all possible numbers of questions that may be on the test?

• 2x + 4y = 100

• 4x + 2y = 100

• 2x = 4y

• 6xy = 100