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AP EAMCET202017 Sep 2020Evening ShiftMathematicsComplex NumberActual

What is the modulus of the complex number ((1+2 i)(-2+i) ) ?

Options

  1. A( 5 )
  2. B5
  3. C(5 5 )
  4. D( 35 )

Correct answer

B. 5

Step-by-step solution

( aligned ( i & +2 i ) (-2+ i )|=| i +2 i| |-2+i & = ( 1^2+2^2 ) ( (-2)^2+1^2 ) & = 5 5 =5 . aligned )

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