Hello, rcmango!
You dropped a minus-sign . . .
We have: .
Use the scalar triple product to conclude that they are coplanar.
. . . . . . . . .
a = 2i+ 3j +k,
b = i - j,
c = 7i + 3j +2k
must use the scalar triple product to conclude that they are coplanar.
i tried this using a *(b x c)
i also said b was b = i - j +0k ??
so i came out with
2(-2-0) + 3(2-0) + 1(3 - -7)
for -4 +6 + 10
don't think this is correct though, i think they need to be 0.
thanks for any help.