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MHT CET20228 Aug 2022Evening ShiftMathematicsVector AlgebraActual

Let u , v and w be vectors such that | u + v + w = 0 | . If | u |=3 , |v| =4 and |w| =5 , then the value of | u v + v w + w u | is

Options

  1. A0
  2. B-25
  3. C47
  4. D25

Correct answer

B. -25

Step-by-step solution

aligned & | u + v + w |^2=| u |^2+| v |^2+| w |^2+2( u v + v w + w u ) & 0^2=3^2+4^2+5^2+2( u v + v w + w u ) & u v + v w + w u =-25 aligned

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