## Calculus 8th Edition

$x-2y-z=-3$
The line of intersection is given as: $a=u \times v$ where $u=\lt1,2,3\gt$ and $v=\lt2,-1,1\gt$ Thus, $a=u \times v=\lt5,5,-5\gt$ and $b=\lt3,-1,5\gt$ Now, $n=a\times b=\lt20,-40,-20\gt$ The general form of the equation of the plane is: $a(x-x_0)+b(y-y_0)+c(z-z_0)=0$ or, $ax+by+cz=ax_0+by_0+cz_0$ Plugging in the values $\lt20,-40,-20\gt$, we get $20(x-3)-40(y-1)-20(z-4)=0$ After simplification, we get $x-2y-z=-3$