Originally Posted by

**Craka** Question states "Find the Cartesian equation of the plane parallel to the plane x+y+2z-5=0 and passing through the point (1,2,-1)".

I approached it like this, vector normal is <1, 1, 2>

then using

$\displaystyle

\begin{array}{l}

n \bullet (r - r_0 ) = 0 \\

< n_1 ,n_2 ,n_3 > \bullet ( < x,y,z > - < x_0 ,y_0 ,z_0 > ) = 0 \\

\end{array}

$

I got this

$\displaystyle

\begin{array}{l}

n \bullet (r - r_0 ) = 0 \\

< n_1 ,n_2 ,n_3 > \bullet ( < x,y,z > - < x_0 ,y_0 ,z_0 > ) = 0 \\

< 1,1,2 > \bullet < x - 1,y - 1,z - 2 > = 0 \\

x - 1 + y - 1 + 2z - 4 = 0 \\

x + y + 2z = 6 \\

\end{array}

$

However the answer is x+y+2z=1 Was I suppose to do something with the 5 in the equation given within question?