Can a brainlet confirm my suspicion that the there is an error

grad (f) = idf/dx + jdf/dy + kdf/dz so it is right

>>8619306

but how dey dun that |gradient(f)|= 1/6 tho

yeah

n=∂f/|∂f| must have
|n| = |(∂f/|∂f|)| = |∂f|/|∂f| = 1
everywhere

but clearly e.g. at
r=(1,0,0)
the n in the pic has value
n=(1/6)·(4,0,0) and thus
|n|=2/3<1

>>8619311
Oops sorry misread, the absolute value would equal 6 because sqrt (16+16+4)

>>8619316

You're ignoring the variables