Answer:
f(x) = -5x + 250
Step-by-step explanation:
* Lets explain how to solve the problem
- In week 10 the manufacturer fixed 200 cars
- In week 15, the manufacturer fixed 175 cars
- the reduction in the number of cars each week is linear
- The form of the linear equation is y = mx + c, where m is the slope of
the line which represent the equation and c is the y-intercept
- The slope of the line m =
where (x1 , y1) and (x2 , y2) are two points on the line
* Lets solve the problem
- Assume that the weeks' number is x and the cars' number is y
∴ (10 , 200) and (15 , 175) are two points on the line which represent
the linear equation between the cars' numbers and the weeks
numbers
∵ Point (x1 , y1) is (10 , 200) and point (x2 , y2) is (15 , 175)
∴ x1 = 10 , x2 = 15 and y1 = 200 and y2 = 175
- Use the rule of the slope above to find m
∴
- Substitute the value of x in the form of the linear equation above
∴ y = -5x + c
- To find c substitute x and y by one the coordinates of one of the
two points
∵ x = 10 when y = 200
∴ 200 = -5(10) + c
∴ 200 = -50 + c
- Add 50 to both sides
∴ 250 = c
- Substitute the value of c by 250
∴ y = -5x + 250, where the number of cars seen each week is y and
x is the number of the week
∵ f(x) = y
∴ f(x) = -5x + 250