Answer: The length of the major axis = 18 units.
Step-by-step explanation:
For equation ellipse: [tex]\dfrac{(x-a)^2}{m^2}+\dfrac{(y-b)^2}{n^2}=1[/tex]
If n>m , then length of major axis = 2n
Otherwise 2m
Given equation:
[tex]\dfrac{(x+2)^2}{64}+\dfrac{(y-1)^2}{81}=1\ \text{ ,which is an ellipse.}\\\\\Rightarrow\ \dfrac{(x+2)^2}{8^2}+\dfrac{(y-1)^2}{9^2}=1[/tex]
9>8
So, the length of the major axis = 2(9) = 18 units.