Step-by-step explanation:
To find the expression for the length, we can use the idea in the equation
[tex]\frac{dA}{dh}=L[/tex]
Where [tex]\frac{dA}{dh}[/tex] is the derivative of A with respect to h.
[tex]\frac{dA}{dh}=24h+15[/tex]
Therefore, the expression for it's length is [tex]24h+15[/tex]