bernoulli's principle(for aeroples)
n n n
sigma Dk= 2n(n+1)/2 n^2+n+2 n^2+n
n(n+1)-1 n^2 n^2+n+2
sigma Dk=n^2+n n^2+n+2 n^2+n
n^2+n-n n^2 n^2+n+2
n o 0
sig Dk= n^2+n 2 0
n^2 0 n+2
n 0 0
n^2+n-n 0 n+2
dis gives
48=2n^2+4n
n=-6 or 4
n=4