Let = 45; , , R. If x( , 1, 2) + y(1, , 2) + z(2, 3, ) = (0, 0, 0) for some x, y, z R, xyz 0, then 6 + 4 + is equal to .
Answer
55
Solution
Componentwise: x + y + 2z = 0, x + y + 3z = 0, 2x + 2y + z = 0
xyz 0 (non-trivial solution) vmatrix & 1 & 2 \ 1 & & 3 \ 2 & 2 & vmatrix = 0
( - 6) - ( - 6) + 2(2 - 2 ) = 0
- 6 - 4 - + 10 = 0
6 + 4 + = 45 + 10 = 55
Answer: 55