17 Consider the system below. Which of the following describes the intersection of the three planes if k = 0? 1 3 0 0 1 -2 -1 O 0 k 2 Select one alternative: O A single point. O A common line. O Three planes coincide. O Three planes with no common intersection.18 The cross product of vectors A and Bis A x B = -i + 3j + 5k. Which of the following is B x A? Select one alternative: Oi -3j - 5k O -i+ 3j +5k O 5i + 3j - k O -i - 3j +5k19 Let u, v and w be vectors in R with u x v = w and u . v = 0. Which of the following must be true about u, v and w ? Select one alternative: Ou . w=0 Ollull = 11811 = 1/20/1 =0 Ollu|11/811 = 1/2011 Ouxuxw=020 Which of the following is not a plane containing the three points P = (1, 1, 1), Q = (2, 1, 0) and R = (1, 0, 3) ? Select one alternative: O (x, y, z) = (1, 0, 3) + s(1, 1, 1) + t(2, 1, 0) O (x, y, z) = (1,0,3) + s(1, 1, -3) + t(0, 1, -2) O (x, y, z) = (1, 0,3) + s(1, 1, -3) + t(1, 0, -1) O (x, y, z) = (1,0,3) + s(1, 0, -1) + t(0, 1, -2)16 Consider an invertible square matrix A. Which of the following statements is true about the homogeneous system Ax = 0? Statement A: The homogeneous system has a unique solution which is x = 0. Statement B: Depending on b, the system Ax = b will either have an infinite number of solutions or no solution. Select one alternative: O Neither A nor B. O A only. O Both A and B. O B only