$x + \dfrac{1}{x} = 5$ आसल्यार, $x^3 + \dfrac{1}{x^3}$ सोदून काडात.
A$110$
B$125$
C$105$
D$100$
Answer & Solution
Correct answer: A. $110$
$(x+1/x)^3=x^3+1/x^3+3(x+1/x)$ वापरून आमी $125=x^3+1/x^3+15$ मेळयतात. देखून $x^3+1/x^3=110$, देखून पर्याय A बरोबर आसा. पर्याय B, $125$, क्रॉस-टर्म $15$ सोडून दिल्ल्यान मेळटा.
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