Subsitution
Consider the equation
y=9 + 3x
If x = -4, what is y?
-3
The starbucks app gives new users 100 points when they sign up, then 5 additional points for each dollar spent.
The equation y = 100 + 5x calculates the points, y, given the number of dollars spent, x.
What is the rate of change in this problem?
The chick-fil-a app gives new users 125 points when they sign up, then 10 additional points for each dollar spent.
The equation y = 125 + 10x calculates the points, y, given the number of dollars spent, x.
What is the starting value in this problem?
125 points
The equation
y = 1500 - 250x
represents the amount of aspirin in a person's body in mg, y, given the number of hours after the aspirin was taken, x.
How much aspirin is in someone's body 2.5 hours after the medication is taken?
875 mg
The equation y = 30 + 4x calculates the value of a bottle of wine, y, given the number of years it's been unopened, x.
What is the slope (rate of change) of this equation?
4 dollars per year
The equation y = 30 + 4x calculates the value of a bottle of wine, y, given the number of years it's been unopened, x.
What is the y-intercept (initial value) of the equation?
$30
The equation y= 10 - 0.03x calculates the amount of printer ink left in Ms. Fink's printer in ml, y, given the number of sheets of paper printed, x.
How much ink is left after she prints 247 pages?
2.59 ml
Kelly's phone battery decreases throughout the day according to the equation y = 100 - 13x, where x is the number of hours since she woke up and y is her phone battery percentage.
What is the slope (rate of change) of the equation?
13 % per hour
Kelly's phone battery decreases throughout the day according to the equation y = 100 - 13x, where x is the number of hours since she woke up and y is her phone battery percentage.
What is the y-intercept (initial value) of the equation?
100%