1 The increase in the length of an ivy plant, in metres, is modelled by the equation
f(x) = 2(1.1)*, where x is the time in weeks.
a Find the initial length of the ivy plant.
b Find the length after 10 weeks.
c Find how long it takes for the plant to
reach a length of 10 metres.
2 A radioactive material has been spilled
on farmland and the quantity remaining
can be modelled by the equation
f(x) = 130(0.85)", where x is the time in
years and f(x) is the mass in grams.
a Find the initial mass of the material.
b Find the mass after four years.
c Write down the equation of the
horizontal asymptote to the graph.
d Calculate how many years it takes before
only half the material remains.