00:02
Is the intersection of the three planes, u plus v plus w plus z is 6, u plus w plus z is 4, and u plus w plus w is 2, align a point or an empty set? what is the intersection if a fourth plane u is negative 1 is included? find a fourth equation that leaves us with no solution.
00:20
Okay, so if u plus v plus w plus z is 6, u plus w plus z is 4 and u plus w is 2.
00:35
Well, u plus w is 2 means that this is 2.
00:39
So then we get that z has to be 2 and u plus w is 2.
00:47
And now we know that z is 2 would give us that v is also 2, which means that you know, u plus w is 2 we have one free variable and then once i determine that one the other one will be known.
01:04
Okay, so i have one free variable because the solution set would be, i don't know, you is equal to 2 minus w, v is 2, w is 2, w is free, and then z would be 2.
01:24
Okay, so the solution set is a line.
01:33
One free variable is aligned, two free variables are plain, 0 free variables is a point, and if it's inconsistent, then it's empty set...