Question

If x+y=8 , 1/x+1/y=1/2 then xy=?

Answer 1

xy = 16

Explanation:

`(1)/(x)` +
`(1)/(y)` =
`(1)/(2)` ( multiply through by 2xy to clear the fractions )

2y + 2x = xy ← factor out 2 from each term on the left side

2(y + x) = xy

substitute x + y = 8 into the left side

2(8) = xy , that is

xy = 16