If \( z=x \cdot f\left(\frac{y}{x}\right)+y\left(\frac{y}{x}\right) \cdot S \cdot T \cdot \cdot x \frac{\partial z}{\partial x}+ \) \( y \cdot \frac{\partial z}{\partial y}=x \cdot f(y / x) \)

Compute the work done by the force field \( F=\langle y, 0, z\rangle \) along the triangle from \( (0,0,0) \) to \( (2,3,4) \) then to \( (2,3,0) \) and then back to \( (0,0,0) \). \( W=\square \)

Compute the divergence of \( F(x, y)=1.2 x i+1.75 y j \) \( \operatorname{div} F=\square \)

3.- \( \quad f(x)=x \ln \cos x \)

Evaluate the line integral. \( \int_{C} 5 z d s \), where \( C \) is the line segment from \( (5,0,1) \) to \( (6,-6,6) \) \( \int_{C} 5 z d s=\square \)

\( \sum _ { y = 1 } ^ { n } \sum _ { x = 1 } ^ { n } 4 x + 7 y + x ^ { 2 } \)