If x +2 y = 10 and 2xy = 9, then one of the value of x − 2y is :

We know that,

If x + y  = n

then, x - y  = \(\sqrt {n^2 - 4xy}\)

If x +2 y = 10

2xy = 9,

So, xy = 4.5

then one of the value of x − 2y = \(\sqrt {10^2 - 4×2×4.5}\)

x − 2y = \(\sqrt {64}\) = 8