You have:(n/?)^2 = 2n

find the square root of both sides:n/? = SQRT(2n)

Multiply both sides by ? to get:n=?SQRT(2n)

Divide both sides by the sqrt(2n) to get:n/SQRT(2n)=?

Now we need to rationalize the denominator:(nSQRT(2n))/(2n)=?

Which simplifies to:SQRT(2n)/2=?