AP EAMCET201923 Apr 2019Morning ShiftMathematicsTrigonometric Ratios & IdentitiesActual
If (x+ 1 x =2 ) and (y+ 1 y =2 ), then (x^3 y^3+ 1 x^3 y^3 = )
Options
- A(2 3( - ) )
- B(2 3( + ) )
- C(2 3( - ) )
- D(2 3( + ) )
Correct answer
C. (2 3( - ) )
Step-by-step solution
It is given that ( array l x+ 1 x =2 x= +i = ( 2 - ) +i ( 2 - ) x=e^ i ( 2 - ) array ) and (y+ 1 y =2 y= +i =e^ i ) Now, (x^3 y^3=e^ i ( 3 2 -3 ) e^ i 3 =e^ i ( 3 2 +(3 -3 ) ) ) ( aligned & = ( 3 2 +3 -3 )+i ( 3 2 +3 -3 ) & = (3 -3 )-i (3 -3 ) aligned ) and ( 1 x^3 y^3 = (3 -3 )+i (3 -3 ) ) So, (x^3 y^3+ 1 x^3 y^3 =2 (3 -3 )=2 3( - ) ) Hence, option (c) is correct.