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AP EAMCET201920 Apr 2019Evening ShiftMathematicsVector AlgebraActual

If | a |=1,| b |=1,| c |=2 and a ( a c )+ b =0 , then ( a c )^2=0

Options

  1. A1
  2. B2
  3. C4
  4. D3

Correct answer

D. 3

Step-by-step solution

If is given that a ( a c )+ b =0 array rlrl & ( a c ) a -( a a ) c & =- b & Let & a c & =x & x a - c & =- b [ | a |=1 a a =1] array On squaring both sides, we get aligned & x^2| a |^2+| c |^2-2 x( a c )=| b |^2 & . x^2+4-2 x^2=1 [as | b |=1 and | c |=2 ] & x^2=3 ( a c )^2=3 aligned Hence, option (d) is correct.

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