AP EAMCET201922 Apr 2019Morning ShiftMathematicsComplex NumberActual
Let ( ) be a root of (x^2+x+ I =0 ) and suppose that a fair die is thrown 3 times. If (a, b ) and (c ) are the numbers shown on the die, then the probability that ( ^a+ ^b+ ^c=0 ), is
Options
- A( 2 36 )
- B( 1 27 )
- C( 1 72 )
- D( 2 9 )
Correct answer
D. ( 2 9 )
Step-by-step solution
Total numbers of ways for ((a, b, c)=6 6 6 ) Here, ( aligned & , ^2 & ^3=1, & ^4= , & ^5= ^2, aligned ) and ( ^6=1 ) Since, ( ^2 ), ( ) are roots of (x^2+x+1=0 ). ( ^a+ ^b+ ^c=0 ) Now, suitable values for ((a, b, c)=6 4 2 ) ( ) Required probability (= 6 4 2 6 6 6 = 8 36 = 2 9 )