Lời giải:
\(x^6-9x^5+30x^4-45x^3+30x^2-9x+1\)
\(=(x^2)^3-3.(x^2)^2.(3x)+3.x^2(3x)^2-(3x)^3+3x^4-18x^3+30x^2-9x+1\)
\(=(x^2-3x)^3+3x^4-18x^3+30x^2-9x+1\)
\(=(x^2-3x)^3+3(x^4-6x^3+9x^2)+3x^2-9x+1\)
\(=(x^2-3x)^3+3(x^2-3x)^2+3(x^2-3x)+1\)
\(=(x^2-3x+1)^3\)