17 cubic units.
The volume (V) of a parallelepiped with one vertex at the origin is given by the absolute value of the scalar vector product of the vectors at the adjacent vertices.
V = |(a x b) · c|
In this case,
a = (1,4,0) = i + 4k + 0j
b = (-2,-5,2) = -2i -5j + 2k
c = (-2,2,1) = -2i + 2j + k
First, let's calculate the cross product of vectors a and b. i.e a x b as follows:
(i) Arrange the vectors in a matrix form
a x b = | i j k |
| 1 4 0 |
| -2 -5 2 |
(ii) Calculate the determinant of the matrix
a x b = i(8 - 0) -j(2-0) + k(-5+8)
a x b = i(8) -j(2) + k(3)
a x b = 8i - 2j + 3k
Secondly, calculate the scalar product of the cross product found above and the vector c as follows;
(a x b) . c = (8i - 2j + 3k) · (-2i + 2j + k)
Multiply like terms
(a x b) . c = (8 * -2)(i.i) + (-2 * 2)(j.j) + (3 * 1)(k.k) [i.i = j.j = k.k = 1]
(a x b) . c = (-16) + (-4) + (3)
(a x b) . c = -16 - 4 + 3
(a x b) . c = -17
Thirdly, find the absolute value of the result found above. i.e
|(a x b) . c| = |-17|
|(a x b) . c| = 17
Therefore, the volume of the parallelepiped is 17 cubic units.
