Solution:
Given the standard form of equation of ellipse:
[tex]\frac{(x-h)^2}{a^2}+\frac{(y-k)^2}{b^2}=1[/tex]Relating it to the equation given as;
[tex]\begin{gathered} \frac{(x-2)^2}{4}+\frac{(y+5)^2}{9}=1 \\ \\ \frac{(x-2)^2}{2^2}+\frac{(y+5)^2}{3^2}=1 \end{gathered}[/tex]The length of the major axis is 2a.
Thus, the length of the major axis of the ellipse is;
[tex]\begin{gathered} a=2; \\ \\ L=2a \\ \\ L=2(2) \\ \\ L=4units \end{gathered}[/tex]