NTA Abhyas JEE Main2020MathematicsDeterminantsPractice
If a 1 2 + a 2 2 + a 3 2 = 1 ,   b 1 2 + b 2 2 + b 3 2 = 4 ,   c 1 2 + c 2 2 + c 3 2 = 9 , a 1 b 1 + a 2 b 2 + a 3 b 3 = 0 , a 1 c 1 + a 2 c 2 + a 3 c 3 = 0 , b 1 c 1 + b 2 c 2 + b 3 c 3 = 0 and A = a 1 a 2 a 3 b 1 b 2 b 3 c 1 c 2 c 3 , then A 4 is equal to
Options
- A36
- B49
- C1296
- D216
Correct answer
C. 1296
Step-by-step solution
A 2 = a 1 a 2 a 3 b 1 b 2 b 3 c 1 c 2 c 3 a 1 a 2 a 3 b 1 b 2 b 3 c 1 c 2 c 3 = a 1 2 + a 2 2 + a 3 2 a 1 b 1 + a 2 b 2 + a 3 b 3 a 1 c 1 + a 2 c 2 + a 3 c 3 a 1 b 1 + a 2 b 2 + a 3 b 3 b 1 2 + b 2 2 + b 3 2 b 1 c 1 + b 2 c 2 + b 3 c 3 a 1 c 1 + a 2 c 2 + a 3 c 3 b 1 c 1 + b 2 c 2 + b 3 c 3 c 1 2 + c 2 2 + c 3 2 = 1 0 0 0 4 0 0 0 9 = 36 ⇒ A 4 = 1296