50 I cena biletu
50+22=72 II cena biletu
50+50x+(50+50x)x=72
50+50x+50x+50x^2=72
50x^2+100x+50-72=0
50x^2+100x-22=0
\Delta = b^2-4ac=100^2-4*50*(-22)=10000+4400=14400
\sqrt{\Delta}=\sqrt{14400}=120
x_1=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-100-120}{100}=-1,1 nie est rozwiązaniem
x_2=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-100+120}{100}=0,2=20\%