Q.

limx(3x+1+3x-1)6+(3x+1-3x-1)6(x+x2-1)6+(x-x2-1)6x3                [2023]

1 is equal to 272  
2 is equal to 9   
3 does not exist  
4  is equal to 27  

Ans.

(4)

limx(3x+1+3x-1)6+(3x+1-3x-1)6(x+x2-1)6+(x-x2-1)6×x3

limxx3×{x3[(3+1x+3-1x)6+(3+1x-3-1x)6]x6[(1+1-1x2)6+(1-1-1x2)6]}

= (3+3)6+(3-3)6(1+1)6+(1-1)6=(23)6+026+0=26·3326=33=27