This is a riddle for fun What question can you never answer yes to?

Abee with velocity vector r'(t) starts out at (5, −5, −3) at t = 0 and flies around for 5 seconds. where is the bee located at time t = 5 if 5 0 r'(u)du = 0?

Ablock of wood is a cube whose side is x in. long. you cut off a 1-inch thick piece from the entire right side. then you cut off a 3-inch thick piece from the entire top of the remaining shape. the volume of the remaining block is 2,002 in3. what are the dimensions of the original block of wood?

What is the missing step in this proof ?