Determine whether the lines given by the vector equations r1=2i + 2j + 3k + s(i + 3j + k) and r2=2i + 3j + 4k + t(i + 4j + 2k) intersect. If they intersect, give the coordinates of their point of intersection.

  i -j +2k . . . at s=t=-1

Step-by-step explanation:

For the lines to intersect, there must be values of s and t that make the coordinates of r1 equal to those of r2.

Equating i coefficients, we have ...

  2 +s = 2 +t

Equating j coefficients, we have ...

  2 +3s = 3 +4t

Equating k coefficients, we have ...

  3 +s = 4 +2t

The first equation tells us s = t. Using t = s in each of the other two equations, they become ...

  2 +3s = 3 +4s   ⇒   s = -1

  3 +s = 4 +2s   ⇒   s = -1

Then the point of intersection is where s = t = -1. That point is ...

  (2 +s)i +(2 +3s)j +(3 +s)k = (2 -1)i +(2 -3)j +(3 -1)k

  = i -j +2k . . . . the point of intersection

go and ask your mom to you