а) 9x²(x-3)=0
x1= 0, x2= 3
б) x²(x-4)-9(x-4)=0
(x-3)(x+3)(x-4)=0
x1= 3, x2= -3, x3= 4
в) y²(y-2)-(y-2)=0
(y-1)(y+1)(y-2)=0
y1= 1, y2= -1, y3= 2
2) пусть x²+2x=t
t²-2t-3=0
D= 4+12= 16
t1= (2+4)/2= 3
t2= (2-4)/2= -1
x²+2x-3=0
D= 4+12=16
x1= (-2+4)/2= 1
x2= (-2-4)/2 = -3
x²+2x+1=0
(x+1)²=0
x3= -1