Answer
$-9x+y+7z=4$
Work Step by Step
The normal to the plane is $n=\lt -9,1,7 \gt$
We know that the standard equation of plane passing through the point $P(x_0,y_0,z_0)$ is written as: $a(x-x_0)+b(y-y_0)+c(z-z_0)=0$
Then, we have for the point $P(1,-1,2)$
$-9(x -1)+1(y +1)+7(z-2)=0$
or, $-9x+9+y+1+7z-14=0$
or, $-9x+y+7z=4$
