1.

यदि `x^(2)-3x+1=0` है तो `x^(3)+1/(x^(3))` का मान क्या होगा?A. 9B. 18C. 27D. 1

Answer» Correct Answer - B
`x^(2)=3x+1=0`
`x^(2)+1=3x`
Divide by `x`
`=(x^(2))/x+1/x`
`implies(3x)/x`
`x+1/x=3`
Cubing both sides
`impliesx^(3)+1/(x^(3))+3x xx 1/x(x+1/x)=27`
`implies x^(3)+1/(x^(3))+3 xx 3=27`
`x^(3)+1/(x^(3))=18`


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