[填空题]
The size of the trunk diame12uhynppsbp( zh19of3zy -qd + +jn5vter ujy bbs-6)2do0fh 8wrof a chestnut oak tree, $d$, in centimetres, can be modelled by the function
$d(t)=9ln(0.25t)$,t≥5,where $t$ is the age, in years, of the tree.
1.Find the size of the trunk diameter of a 10-year-old chestnut oak tree. d =
2.The size of the trunk diameter of a chestnut oak tree is 15 cm. Find its age. t =
A chestnut oak tree can be harvested for wood when the size of its trunk diameter reaches 20 cm.
3.Find the age of the chestnut oak tree when it is old enough to be harvested for timber. t =