Let be three distinct real numbers, none equal to one. If the vectors and are coplanar, then is equal to
- (A)1✓ Correct
- (B)-1
- (C)-2
- (D)2
Answer: (A)
Solution
Three vectors are coplanar if their scalar triple product is zero:
Expanding:
Rearranging:
This gives:
Dividing by and manipulating:
Dividing through:
Since :
Expanding:
Rearranging:
This gives:
Dividing by and manipulating:
Dividing through:
Since :
JEE Main · 2023 · 12 Apr 2023 · Shift 1 · Single correct option