यदि `4b^(2)+1/(b^(2))=2` है तो `8b^(3)+1/(b^(3))` का मान क्या है?

Options

A. 0
B. 1
C. 2
D. 5

Answer

A

Explanation

`4b^(2)+1/(b^(2))=2`
`(2b)^(2)+(1/b)^(2)+4-4=2`
`(2b+1/b)^(2)-4=2`
`(2b+1/b)^(2)=6`
`2b+1/b=sqrt(6)`
Take cube both sides
`(2b+1/b)^(3)=(sqrt(6))^(3)`
`8b^(3)+1/(b^(3))+3xx2bxx1/b(2b+1/b)=6sqrt(6)`
`8b^(3)+1/(b^(3))+6sqrt(6)=6sqrt(6)`
`8b^(3)+1/(b^(3))=0`