যদি x4-x2+1=0 হয়, তবে, x3+1/x3 = কত?
Solution
Correct Answer: Option D
x4 - x2 + 1 = 0
=> x4 + 1 = x2
=> x4 + 1/x2 = 1
=> x2 + 1/x2 = 1
=> (x+1/x)2 - 2.x.1/x = 1
=> (x+1/x)2 = 3
=> x+1/x = √3
আবার,
x3 +1/x3
= (x+1/x)3 - 3.x.1/x (x+1/x)
= (√3)3 - 3√3
= 3√3 - 3√3
= 0
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