Because the y value is the time it takes to complete 1 lap.
We have a three unknown, 4 equation homogeneous system. These always have at least (0,0,0) as a solution. Let's write the equations, one column at a time.
1a + 0b + 0c = 0
-1a + 1b +0c = 0
0a - 1b + c = 0
0a + 0b + -1 c = 0
We could do row reduction but these are easy enough not to bother.
Equation 1 says
a = 0
Equation 4 says
c = 0
Substituting in the two remaining,
-1(0) + 1b + 0c = 0
b = 0
0(0) - 1b + 0 = 0
b = 0
The only 3-tuple satisfying the vector equation is (a,b,c)=(0,0,0)
Answer: The amswer is D because -1 + 1 = 0
Answer:

Step-by-step explanation:
∵ The volume of the pyramid = 1/3 base area × height
∵ The base is equilateral Δ with side length 4
∴ The area of the bast = 1/4 × 4² × √3 = 4√3 units²
To get the height of the pyramid draw it from the vertex of the top of the pyramid ⊥ to the base on the centro-id of the base which divides the height of the triangle two ratio 2:1 from the vertex of the triangle
∵ The height of the base = √(4² - 2²) =√12 = 2√3
∴ 2/3 the height = 4√3/3 ⇒ (2:1 means 2/3 from the height)
∴ The height of the pyramid = √[4² - (4√3/3)²] = √[16 - 48/9]
∴ h = 4√2/√3 (4√6/3 in its simplest form)
∴ V = 1/3 × 4√3 × 4√2/√3 = 16√2/3 units³
∴ 
6 because if you take the 2.04679 then divide you would get 6.