Răspuns:
18
afolosind formula(a-b)^2=a^2-2ab+b^2
avem
4x^2-12x+9<4x^2-4x+1=
-12x+9<-4x+1
-12x+4x<1-9
-8x<-8x
x>1
b=
9x^2+12x+4>9x^2+24+16=
12x+4>24x+16=
12x-24x>16-4=
-12x>12
x<-1
c=
16x^2-24x+9<16x^2-8x+1=
-24x+9<-8x+1=
-24x+8<1-9=
-16x<-8=
x>1/2
d
25x^2-20x+4>1+10x+25x^2=
-20x+4>1+10=
-20x+10>1-4=
-30x>-3=
x<1/10
