Final answer:
The given statement ff is true for scalar field f and vector fields f and g.
Step-by-step explanation:
The given statement, ff is a true identity for scalar field f and vector fields f and g. To prove this identity, we need to show that the left-hand side (LHS) is equal to the right-hand side (RHS).
LHS = ff = f * f = f2
RHS = f. = f * (f . g) = f * (g . f) = f * (g * f)
We can see that LHS = RHS, so the given identity is true.