If a² + b² = 45 and ab =18, find (1/a)+(1/b)

প্রশ্ন: If a² + b² = 45 and ab =18, find (1/a)+(1/b)

Solution:
Given,
a² + b² = 45
ab = 18

Now,
(1/a) + (1/b) = (b + a)/ab
= √(a + b)²/ab
= √(a² + b² + 2ab)/ab
= √{45 + (2 × 18)}/18
= √81/18
= 9/18
= 1/2