Class 12 Vector Algebra · Short Answer2 Marksvector_identities
Class 12 Maths · Vector Algebra · Short Answer #106
For a unit vector a, (x−a)·(x+a)=15. Find |x|.
✅ Step-by-Step Solution
Final Answer: 4
- Expand (x−a)·(x+a)=|x|²−|a|².
- Thus |x|²−1=15, giving |x|²=16.
- The nonnegative magnitude is |x|=4.
📋 CBSE Stepwise Marking Scheme
- [0.5 marks] Expand (x−a)·(x+a)=|x|²−|a|².
- [1 mark] Thus |x|²−1=15, giving |x|²=16.
- [0.5 marks] The nonnegative magnitude is |x|=4.
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