1.

यदि `x^(3)+y^(3)=35` और `x+y=5` है तो `1/x+1/y` का मान क्या होगा?A. `1/3`B. `5/6`C. `6`D. `2/3`

Answer» Correct Answer - B
`x^(3)+y^(3)=35`
`implies x+y=5`
Take cube on both sides
`(x+y)^(3)=(5)^(3)`
`x^(3)+y^(3)+3xy(x+y)=125`
`35+3xy(5)=125`
`15xy=125-35`
`15xy=90`
`xy=6`
`:. 1/x+1/y=(x+y)/(xy)=5/6`


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