Verified answer

a) a=2, b= -1, c= -6

б) a=4, b=9, c= 20

a) (x-3)(x+3)=0

x1=3, x2= -3

б) x²≠-9

x∈∅

в) x(x-9)=0

x1= 0, x2= 9

г) x(x+9)=0

x1= 0, x2= -9

д) 2x²-x-6=0

D= 1+48= 49

x1= (1+7)/4= 2

x2= (1-7)/4= -1,5

е) 4x²+9x+20=0

D= 81-320

D<0

x∈∅

а) x²+2x-8/x²+4x= (x²-2x+4x-8)/x(x+4)= (x+4)*(x-2)/x(x+4)= (x-2)/x или 1- 2/x

б) y²-y-6/y²+2y= (y²+2y-3y-6)/y(y+2)= (y-3)(y+2)/y(y+2)= (y-3)/y или 1- 3/y