Question

combinari de n luate cate 1 =36-aranjamente de n luate cate 2

Answer 1

n! /(n-1)!=36-n!/(n-2)!=>(n-1)!n/(n-1)!=36-(n-2)!(n-1)n/(n-2)!=>n=36-n^2-n=>n+n^2+n=36=>2n+n^2-36=0=>n^2+2n-36=0=>delta=4+36*4*2=4+36*8=4+288=292=>x1=-2+rad(292)/2
X2=-2-rad(292) /2