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AP EAMCET202017 Sep 2020Evening ShiftMathematicsVector AlgebraActual

If ( a , b , c ) and ( r ) are vectors such that ( a ) is not perpendicular to ( b r b = c b ) and ( r a = 0 ) then ( r = )

Options

  1. A( c + ( c a ) ( b a ) b )
  2. B( b - ( c a ) ( b a ) c )
  3. C( c - ( c a ) ( b a ) b )
  4. D( b + ( c a ) ( b a ) c )

Correct answer

C. ( c - ( c a ) ( b a ) b )

Step-by-step solution

Given, ( aligned & r b = c b & ( r - c ) b = 0 & r - c is parallel to b . & ( r - c )= b & r = c + b aligned ) or ( r = c + b ) ...(i) Also, ( r a =0 ( c + b ) a =0 ) ( c a + b a = 0 ) or ( =- ( c a b a ) ) ...(ii) So, from Eq. (i) we substitute ' ( ) ' from Eq. (ii), we get ( r = c - ( c a b a ) b )

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