God, these two symbols are vector operation symbols in the "multivariate calculus" branch of higher mathematics, and they are only used for vectors, not abbreviations for division.

Suppose a three-dimensional vector F(x, y, z) = A*I+B*J+C*K, where i, j, K j and k are three directions of three dimensions, then

Div F = dA/dx+dB/dy+dC/dz ... is a vector.

Curl f = (dc/dy-db/dz) * i+(da/dz-dc/dx) * j+(db/dx-da/dy) * k ...

For example, f = (x+2y) * i+(x * x+3z) * j+(xy-4yz) * k.

div F = 1 + 0 - 4y = 1 - 4y

Curl F = (x-4z-3)*I+(0-y)*J+(2x-2)*K