1)x²+4x+4-4x²+12x-9+8x-40<0⇒-3x²+24x-45<0⇒x²-8x+15>0
x1+x2=8 U x1*x2=15⇒x1=3 U x2=5⇒x<3 U x>5
x²-x-42≤0⇒x1+x2=1 U x1*x2=-42⇒x1=-6 U x2=7⇒-6≤x≤7
x∈[-3;3) U (5;7]
2)x²-4x+4-4x²-12x-9+8x+40≤0⇒-3x²-8x+35≤0⇒3x²+8x-35≥0
D=64+420=484
x1=(-8-22)/6=-5 x2=(-8+22)/6=7/3
x≤-5 U x≥7/3
x²+x-42<0⇒x1+x2=-1 U x1*x2=-42⇒x1=-7 U x2=6⇒-7<x<6<br>x∈(-7;-5] U [7/3;6)
3)(x+4)/(x-2)≤0
x=-4 x=2
-4≤x≤2
x(x-5)<0<br>x=0 x=5
0x∈(0;2]