Question

2. Forrest Lumber uses the function
S(t) = -105t + 840

to determine the salvage value S(t), in dollars, of a table saw t years after its purchase. How long will it take the saw to depreciate completely?
9 years
10 years
8 years
7 years

Answer 1

When it says "depreciate completely", that means the point where its salvage value, S(t), is equal to 0.

Answer 2

So if S(t) = 0,
then 0 = -105t + 840

Then you just need solve for "t"

Answer 3

So what is T