а)
9х²-6х+1+
108х²-72х+12+3(х²-9)=4(16х²-8х+1)-12
108х²-72х+12+3х²-27=64х²-32х+4-12
111х²-72х-15=64х²-32х-8
111х²-72х-15-64х²+32х+8=0
47х²-40х-7=0
Д=-40²-4*47*(-7)=2916
х=40±54/94
х=40+54/94=1
х=40-54/94=-7/47
Ответ
х1=-7/47 , х2=1
б)


5(х²-х)-2(4х²-4х+1)=2х²+х-1-40
5х²-5х-8х²+8х-2=2х²+х-41
-3х²+3х-2=2х²+х-41
-3х²+3х-2-2х²-х+41=0
-5х²+2х+39=0
5х²-2х-39=0
Д=-2²-4*5*(-39)=784
х=2±28/10
х=2+28/10=3
х=2-28/10=-13/5
Ответ
х1=-13/5 , х2=3
в)

3(25х²+30х+9)-4(х²-4)-6(9х²+6х+1)=0
75х²+90х+27-4х²+16-54х²-36х-6=0
17х²+54х+37=0
Д=54²-4*17*37=400
х=-54±20/34
х=-54+20/34=-1
х=-54-20/34=-37/17
Ответ
х1=-37/17 , х2=-1
г)


5(х²+8х+16)-4(2х²+х-1)=20х²+120х+160
5х²+40х+80-8х²-4х+4=20х²+120х+160
-3х²+36х+84=20х²+120х+160
-3х²+36х+84-20х²+120х+160=0
-23х²-84х-76=0
23х²+84х+76=0
Д=84²-4*23*76=64
х=-84±8/46
х=-84+8/46=-38/23
х=-84-8/46=-2
Ответ
х1=-2 , х2=-38/23