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(2n+4) * n/2 = 99

cine mi-l rezolva corect are coroniță


Răspuns :

2n*n/2+4*n/2=99
n6^2+2n=99
n^2+2n-99=0
delta este 4-4*(-99)=400
n1=(-2+20)/2=18/2=9
n2=(-2-20)/2=-22/2=-11
(2n+4)*n=99*2
2n^2+4n-198=0
d=16+4*198*2=1600=40^2
n1=(-4-40)/2*2=-44:4=-11
n2=(-4+40)/4=36/4=9
r/s:n=-11
n=9