$\mathbfa \times \mathbfb = \beginvmatrix \mathbfi & \mathbfj & \mathbfk \ 2 & 1 & -1 \ 1 & -2 & 3 \endvmatrix = (3 - 2)\mathbfi - (6 - (-1))\mathbfj + (-4 - 1)\mathbfk = \mathbfi - 7\mathbfj - 5\mathbfk$.
: While often focusing on newer editions (5th–7th), it provides verified explanations for common problems found in Zill's texts. Internet Archive problem number from the vector calculus section to solve? Solucionario Cálculo Vectorial Zill 3ª Ed. | PDF - Scribd