## Calculus: Early Transcendentals 8th Edition

$x=-1-10t,y=1-16t,z=2-12t$
At points (-1,1,2): $\nabla P \times \nabla Q=\lt -2,2,-1 \gt \times \lt -8,2,4 \gt=\lt 10, 16, 12 \gt$ Formula to calculate tangent line equation is: $\dfrac{(x_2-x_1)}{f_x(x_1,y_1,z_1)}=\dfrac{(y_2-y_1)}{f_y(x_1,y_1,z_1)}=\dfrac{(z_2-z_1)}{f_x(x_1,y_1,z_1)}$ This implies $\dfrac{(x+1)}{5}=\dfrac{(y-1}{8}=\dfrac{(z-2)}{6}$ Hence, the parametric line of equations are: $x=-1-10t,y=1-16t,z=2-12t$