What are the values of x for which the angle between the vectors 2x^2 i +3x j + k and i -2 j +x^2 k is obtuse?

NDA 2022 Mathematics question

What are the values of for which the angle between the vectors and is obtuse?

Answer: (A)

The angle is obtuse when the dot product is negative: . This holds for .

Question ID VK-029480