Mathematics
Grade10
Easy
Question
Luke has a $ 25 gift card to pay for video game rentals. Which piecewise-defined function best represents the balance remaining on the gift card, f(x) , after each game rental, x?
- f(x) = 25 − 3x , 0 ≤ x ≤ 5
f(x) = 15 − x , 6 ≤ x ≤ 10 - f(x) = 25 − 3x , 0 < x <5
f(x) = 15 − x , 6 < x < 10 - f(x) = 25 + 3x , 0 ≤ x ≤ 5
f(x) = 15 + x , 6 ≤ x ≤ 10 - f(x) = 25 + 3x , 0 < x < 5
f(x) =15 + x , 6 < x < 10
f(x) = 15 − x , 6 ≤ x ≤ 10
f(x) = 15 − x , 6 < x < 10
f(x) = 15 + x , 6 ≤ x ≤ 10
f(x) =15 + x , 6 < x < 10
Hint:
Observe the trend in which the numbers are decreasing. In this problem they are decreasing by 3.
The correct answer is: f(x) = 25 − 3x , 0 ≤ x ≤ 5
f(x) = 15 − x , 6 ≤ x ≤ 10
x = 5, f(x) = 25 – 3x = 25 – 15 = 10
x = 6, f(x) = 15 – 6 = 9
Option A is the correct one.
We are not taking the second option because it can be that he rents 0 games or he rents 5 games.
So we have to include both of them.
Observe the problem carefully and look out for base cases.
