Question

if 1/a +1/b=1/c and ab = c then the average of a and b is

Answer 1

given ab=c
1/a+1/b=1/c
(a+b)/ab=1/c
(a+b)/c=1/c
⇒a+b=1
now,
      ( a+b)/2=1/2

Answer 2

Given:
$1/a + 1/b =1/c$
$ab=c$

Cross-multiplying, we get $b/ab + a/ab = 1/c (a+b)/ab = 1/c$

We can cancel the denominators as $ab=c$.

Now, we have a+b=1, so the average of a and b is (a+b)/2 = 1/2 = 0.5