Final answer:
To compute Fᵣₛₜ, we take the third partial derivatives of the function F(r,s,t) = -r(9s²+9t³) with respect to r, s, and t. The final result after taking the partial derivatives in sequence is that Fᵣₛₜ equals 0.
Step-by-step explanation:
To compute Fᵣₛₜ, which represents the third partial derivative of the function F(r,s,t) = -r(9s²+9t³) with respect to r, s, and then t, we need to perform the following steps:
- Take the partial derivative of F with respect to r, denoted as Fᵣ.
- Next, take the partial derivative of Fᵣ with respect to s, resulting in Fᵣₛ.
- Finally, take the partial derivative of Fᵣₛ with respect to t, which gives us Fᵣₛₜ.
Performing these calculations, we find:
- Fᵣ = -9s² - 9t³
- Fᵣₛ = -18s
- Fᵣₛₜ = 0
Therefore, Fᵣₛₜ = 0.