x2 - 7x + 1 = 0 হলে (x4 + 1)/x2 এর মান কত?
সমাধান
সঠিক উত্তর: Option B
x2 - 7x + 1= 0
⇒ x2 + 1 = 7x
⇒ x + (1/x) = 7
(x4 + 1/x2
= x2 + (1/x2)
= (x + 1/x)2 - 2
= 72 - 2
= 49 - 2
= 47
⇒ x2 + 1 = 7x
⇒ x + (1/x) = 7
(x4 + 1/x2
= x2 + (1/x2)
= (x + 1/x)2 - 2
= 72 - 2
= 49 - 2
= 47
