\(8x^3-\left(x+1\right)^3=3x-3\)
\(8x^3-x^3-2x^2-x-x^2-2x-1=3x-3\)
\(7x^3-3x^2-6x+2=0\)
\(\left(7x^2+4x-2\right)\left(x-1\right)=0\)
\(\left[{}\begin{matrix}x=1\\x=-\frac{2-3\sqrt{2}}{7}\end{matrix}\right.;-\frac{2+3\sqrt{2}}{7}}\)
8\(x^3\)-\(\left(x+1\right)^3\)=3x-3
Bạn dùng 7 HĐT đáng nhớ ấy(\(A^3\)-3\(A^2B\)+\(3AB^2\)-\(B^3\))