1. Considering 2 planes with equations:

x + 2y - 3z = 1
x + 2y - 3z = 18

(a) Given (a,b,c) a point on the first plane, find the point where the line perpendicular to both planes passes by (a,b,c) and through the 2nd plane.

To find the point where the line perpendicular to both planes passes through a given point (a, b, c) on the first plane and through the second plane, we need to find the direction vector of the line and then find the point of intersection between the line and the second plane.

First, let's find the direction vector of the line. The direction vector of a line perpendicular to two planes is given by the cross product of the normal vectors to the two planes.

Let's find the normal vectors of the two planes:

For the first plane:
x + 2y - 3z = 1

The coefficients of x, y, and z in the equation represent the components of the normal vector to the plane. So, the normal vector to the first plane is (1, 2, -3).

For the second plane:
x + 2y - 3z = 18

Again, the coefficients of x, y, and z represent the components of the normal vector to the plane. So, the normal vector to the second plane is also (1, 2, -3).

Now, let's find the cross product of the two normal vectors to get the direction vector of the line:

(1, 2, -3) x (1, 2, -3) = (0, 0, 0)

Since the cross product is the zero vector, it means that the two planes are parallel, and there is no unique line perpendicular to both planes. In this case, the line can be any line parallel to the two planes.

However, if the two planes were not parallel, the resulting direction vector would be the direction of the line.

To find the point of intersection between this line and the second plane, we need to substitute the coordinates (a, b, c) into the equation of the second plane and solve for the remaining variable.

For the second plane:
x + 2y - 3z = 18

Substituting the coordinates (a, b, c):
a + 2b - 3c = 18

This equation represents a plane parallel to the second plane, passing through the point (a, b, c). To find the point of intersection between this plane and the second plane, we need additional information or conditions to solve for the remaining variables.