Помогите срочно номера 3, 6, 7 и 8

3 (a^5-2a³+a):(1/a²-1)=a(a^4-2a²+1):(1-a²)/a²=a(1-a²)²*a²/(1-a²)=a³(1-a²) a=3 27*(1-9)=27*(-8)=-216 6 [x(x-y)-(x-y)]/2(x-3)=(x-y)(x-3)/2(x-3)=(x-y)/2 x=y+5 (y+5-y)/2=5/2=2,5 7 x3=a,a≠0 a=4/a-3 a²+3a-4=0 a1+a2=-3 U a1*a2=-4 a1=-4⇒x³=-4⇒x=-∛4 a2=1⇒x³=1⇒x=1 -∛4*1=-∛4 8 x(x²-2x-3)/x(x-3)=(x-3)(x+1)/(x-3)=x+1 x+1=0 x=-1