(1-a)*(1-b)*(1-c) = (-1)*(a-1)*(-1)*(b-1)*(-1)*(c-1)=-(a-1)(b-1)(c-1)
-(a-1)(b-1)(c-1)≥8abc
(a-1)(b-1)(c-1)≤8abc
(a-1)*(b-1)*(c-1)≤ 2a*2b*2c
a-1≤2a; b-1≤2b; c-1≤2c ⇒ (a-1)*(b-1)*(c-1)≤2a*2b*2c
Х² - 3х - 4 ≥ 0
х² - 3х - 4 = (х + 1)(х - 4)
<span>х² - 3х - 4 = 0
</span>D= (-3)² - 4 · 1 · (|-4) = 9 + 16 = 25; √25 = 5
x₁ = (3 - 5)/2 = -1
x₂ = (3 + 5)/2 = 4
(х + 1<span>)(х - 4) </span>≥ 0
+ - +
________|_________|_____
-1 4
x ∈ (-∞; -1]∪[4; +∞)
=-3ху-2ху²+4у²+21х²+14х²у-28ху=4у²+21х²+14х²у-2ху²-31ху
(30x+6)/(x+3)·(x²-9)/(x²-4)=6(5x+1)(x²-9)/(x+3)(x²-4)=
6·(5x+1)(x-3)(x+3)/(x+3)(x²-4)=6·(5x+1)(x-3)/(x²-4);