1) x^4-81=0
(x-3)(x+3)(x²+9)=0
x²+9>0 при любом х
х=3б х=-3
2) 256x^5-x=0
x(4x-1)(4x+1)(16x²+1)=0
16x²+1>0 при любом х
x=0,x=1/4,x=-1/4
3) (x-1)^2-9=0
(x-1-3)(x-1+3)=0
(x-4)(x+2)=0
x=4,x=-2
4) 81-(y+1)^2=0
(9-y-1)(9+y+1)=0
(8-y)(10+y)=0
y=8,y=-10
5) (x+3)^2-4x^2=0
(x+3-2x)(x+3+2x)=0
(3-x)(3x+3)=0
x=3,x=-1
6) (6x^2-(x-5)^2=0
(√6x-x+5)(√6x+x-5)=0
(x(√6-1)+5)(x(√6+1)-5)=0
x=5/(1-√6)=-(1+√6), x=5/(√6+1)=√6-1
7) x^2+3x+2=0
x1=x2=-3 U x1*x2=2
x1=-2,x2=-1
8) x^2-4x-5=0
x1+x2=4 u x1*x2=-5
x1=-1, x2=5