1
x(2+ay)=1-ay
xa+xay=1-ay
xay+ay=1-xa
y(xa+a)=1-xa
y=(1-xa)/(xa+a)
2
S=12t²+8/t-5t
S=(12t³+8t-5t²)/t
V=6t-5
6t=V+5
t=(v+5)/6
S=[12(v+5)³/216+8-5(v+5)²/36]:(v+5)/6=
=[12(v+5)³+8*216-30(v+5)²]/216*6/(v+5)=[2(v+5)³+288-5(v+5)³]/([6(v+5)]=
=(2v³+30v²+150v+250+288-5v²-50v-125)/(6v+30)=
=(2v³+25v²+100v+413)/(6v+30)