(1) 0 (2) 1 (3) 2 (4) 5
Solution:
(2b+1/b)2
= 4b2+1/b2+2*2b*1/b =2 + 4 = 6
⇒ 2b+1/b =√6
.’. 8b3+1/b3
= (2b+1/b)3 -3*2b*1/b(2b+1/b)
= (√6)3 -6(√6)
= 6(√6) – 6(√6) =0
Then the option is (1)
(1) 0 (2) 1 (3) 2 (4) 5
(2b+1/b)2
= 4b2+1/b2+2*2b*1/b =2 + 4 = 6
⇒ 2b+1/b =√6
.’. 8b3+1/b3
= (2b+1/b)3 -3*2b*1/b(2b+1/b)
= (√6)3 -6(√6)
= 6(√6) – 6(√6) =0
Then the option is (1)