1) Expand and simplify: (-2a + 3b) dot (5a - b). (a and b being vectors)

2) Explain how to prove if 4 given points are coplanar. Determine if A(3, 1, 0), B(2, -3, 1), C(-1, 0, 4) and D(5, -6, -2) are coplanar.

Thanks, I'm completely stumped on both.