a: \(\Leftrightarrow x^3+9x^2+27x+27-3x^2-x+8x^3+1=28\)
\(\Leftrightarrow9x^3+6x^2+26x=0\)
\(\Leftrightarrow x=0\)
b: \(\Leftrightarrow8x^2-12x^2+6x-1-8x^3+12x^2=5\)
=>6x=6
hay x=1
c: \(\Leftrightarrow x^3+3x^2+3x+1-x^3+3x^2-3x+1-6x^2+12x-6=-10\)
=>12x-4=-10
=>12x=-6
hay x=-1/2