(x−a)⋅(x+a)=∣x∣2−∣a∣2=∣x∣2−1=8. So ∣x∣2=9, hence ∣x∣=3.
If a is a unit vector and (x−a)⋅(x+a)=8 then ∣x∣ is
Held on 23 Aug 2022 · Verified 13 Jul 2026.
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