8
ОЗ 10
y²+10y-10y-25=200
y²=225
y1=-15
y2=15
9
a)x≠5
x²-8x=-15
x²-8x+15=0
x1+x2=8 U x1*x2=15
x1=3
x2=5 не удов усл
б)x≠0;x≠3
x²-9=2x²+10x
x²+10x+9=0
x1+x2=-10 U x1*x2=9
x1=-9
x2=-1
11
(y+3)/(y-3)-(y-3)/(y+3)=3/2
y≠3;y≠-3
2(y+3)²-2(y-3)²=3(y+3)(y-3)
2y²+12y+18-2y²+12y-18=3y²-27
3y²-24y-27=0
y²-8y-9=0
y1+y2=8 U y1*y2=-9
y1=-1
y2=9