If a2 + b2 = 45 and ab = 18, find (1/a) + (1/b)
সমাধান
সঠিক উত্তর: Option B
দেওয়া আছে,
ab = 18
a2 + b2 = 45
⇒ (a + b)2 - 2ab = 45
⇒ (a + b)2 - 36 = 45
⇒ (a + b)2 = 81
∴ a + b = 9
এখন,
(1/a) + (1/b)
= (b + a)/ab
= 9/18
= 1/2
ab = 18
a2 + b2 = 45
⇒ (a + b)2 - 2ab = 45
⇒ (a + b)2 - 36 = 45
⇒ (a + b)2 = 81
∴ a + b = 9
এখন,
(1/a) + (1/b)
= (b + a)/ab
= 9/18
= 1/2
