A new car cost 21000 and depreciates linearly to value of 10

A new car cost $21,000 and depreciates linearly to value of $10,000 after 3 years write a formula expressing V (value) as a function of t (age)

Solution

at t=0 cost is $21000

so point is (0,21000)

after 3 years the cost is $10500

(3,10500)

we got points now

slope of the line is (m) = y2 -y1/x2-x1

m = 10500 - 21000 / 3-0

m = -10500/3

m= -3500

now line is y -y1 = m(x-x1)

y -21000 = m(x-0)

y = -3500x +21000

so line is y = -3500x+21000

here x is number if years