Gene G. answered • 11/28/16

Tutor

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You can do it! I'll show you how.

Your equation represents exponential growth not decay (decrease).

For decay, the exponent needs to be negative, or the base (the 2) would have to be between 0 and 1.

For decay, the exponent needs to be negative, or the base (the 2) would have to be between 0 and 1.

Assuming the equation should be V=45*2

^{-0.9t}, here is what you would do:At t=0 the book is new. -0.9t = 0, so

V = 45*2

^{0}= 45*1 = 45. This is the original cost.At t=2, -0.9t = -1.8

V = 45*2

^{-1.8}= 45*0.2872 ≈ 12.92At t=10,

V = 45*2

^{-9}= 45*0.00195 ≈ 0.09Domain:

Time begins at 0 when the book is new and increases from there.

0 < t <∞

Range

Value begins at 45 and decreases toward zero. It can never reach zero.

0 < V ≤ 45