6
x≠-1 x≠-1/3
2-x(3x+1)=4(x+1)
2-3x²-x-4x-4=0
3x²+5x+2=0
D=25-24=1
x1=(-5-1)/6=-1 не удов усл
x2=(-5+1)/6=-2/3
Ответ х=-2/3
7
4x^4-5x²+1≠0
x²=a
4a²-5a+1=0
D=25-16=9
a1=(5-3)/8=1/4
x²≠1/4
x≠-1/2 x≠1/2
a2=(5+3)/8=1
x²≠1
x≠-1 x≠1
x∈(-∞;-1) U (-1;-1/2) U (-1/2;1/2) U (1/2;1) U (1;∞)