1/x + 1/y = 3 এবং (1/x2) - (1/y2) = 9 হলে 1/x - 1/y = কত?
সমাধান
সঠিক উত্তর: Option C
দেওয়া আছে,
1/x + 1/y = 3
এবং (1/x2) - (1/y2) = 9
এখন,
(1/x2) - (1/y2) = 9
⇒ (1/x + 1/y)(1/x - 1/y) = 9
⇒ 1/x - 1/y = 9/3 [ 1/x + 1/y = 3 ]
∴ 1/x - 1/y = 3
1/x + 1/y = 3
এবং (1/x2) - (1/y2) = 9
এখন,
(1/x2) - (1/y2) = 9
⇒ (1/x + 1/y)(1/x - 1/y) = 9
⇒ 1/x - 1/y = 9/3 [ 1/x + 1/y = 3 ]
∴ 1/x - 1/y = 3
