a) \(27x^3+27x^2+9x+1=\left(3x+1\right)^3\)

b) \(-x^3-3x^2-3x-1=-\left(x^3+3x^2+3x+1\right)=-\left(x+1\right)^3\)

c) \(-8+12x-6x^2+x^3=\left(x-2\right)^3\)

Câu b đề sai nha bạn.

a) \(x^3+9x^2+27x+27=\left(x+3\right)^3\)

b) \(3\sqrt{3x^3}+18x^2+12\sqrt{3x}+8=\left(\sqrt{3x}+2\right)^3\)

c) \(\dfrac{1}{4}-x^2=\left(\dfrac{1}{2}-x\right)\left(\dfrac{1}{2}+x\right)\)

a: x^3-7x-6

=x^3-x-6x-6

=x(x-1)(x+1)-6(x+1)

=(x+1)(x^2-x-6)

=(x-3)(x+2)(x+1)

b: =2x^3+x^2-2x^2-x+6x+3

=x^2(2x+1)-x(2x+1)+3(2x+1)

=(2x+1)(x^2-x+3)

c: =2x^3-3x^2-2x^2+3x+2x-3

=x^2(2x-3)-x(2x-3)+(2x-3)

=(2x-3)(x^2-x+1)

d: =2x^3+x^2+2x^2+x+2x+1

=(2x+1)(x^2+x+1)

e: =3x^3+x^2-3x^2-x+6x+2

=(3x+1)(x^2-x+2)

f: =27x^3-9x^2-18x^2+6x+12x-4

=(3x-1)(9x^2-6x+4)

a) \(x^3-7x-6\)

\(=x^3-x-6x-6\)

\(=\left(x^3-x\right)-\left(6x+6\right)\)

\(=x\left(x^2-1\right)-6\left(x+1\right)\)

\(=x\left(x+1\right)\left(x-1\right)-6\left(x+1\right)\)

\(=\left(x+1\right)\left(x^2-x-6\right)\)

b) \(2x^3-x^2+5x+3\)

\(=2x^3+x^2-2x^2-x+6x+3\)

\(=\left(2x^3+x^2\right)-\left(2x^2+x\right)+\left(6x+3\right)\)

\(=x^2\left(2x+1\right)-x\left(2x+1\right)+3\left(2x+1\right)\)

\(=\left(x^2-x+3\right)\left(2x+1\right)\)

c) \(2x^3-5x^2+5x+1\)

\(=2x^3-3x^2-2x^2+3x+2x-3\)

\(=\left(2x^3-3x^2\right)-\left(2x^2-3x\right)+\left(2x-3\right)\)

\(=x^2\left(2x-3\right)-x\left(2x-3\right)+\left(2x-3\right)\)

\(=\left(x^2-x+1\right)\left(2x-3\right)\)

d) \(2x^3+3x^2+3x+1\)

\(=2x^3+x^2+2x^2+x+2x+1\)

\(=\left(2x^3+x^2\right)+\left(2x^2+x\right)+\left(2x+1\right)\)

\(=x^2\left(2x+1\right)+x\left(2x+1\right)+\left(2x+1\right)\)

\(=\left(2x+1\right)\left(x^2+x+1\right)\)

e) \(3x^3-2x^2+5x+2\)

\(=3x^3+x^2-3x^2-x+6x+2\)

\(=\left(3x^3+x^2\right)-\left(3x^2+x\right)+\left(6x+2\right)\)

\(=x^2\left(3x+1\right)-x\left(3x+1\right)+2\left(3x+1\right)\)

\(=\left(3x-1\right)\left(x^2-x+2\right)\)

f) \(27x^3-27x^2+18x-4\)

\(=27x^3-9x^2-18x^2+6x+12x-4\)

\(=\left(27x^3-9x^2\right)-\left(18x^2-6x\right)+\left(12x-4\right)\)

\(=9x^2\left(3x-1\right)-6x\left(3x-1\right)+4\left(3x-1\right)\)

\(=\left(3x-1\right)\left(9x^2-6x+4\right)\)

\(3x^3-21x^2+27x=3x\left(x^2-7x+9\right)\)

\(3x^3-21x^2+27x=3x\left(x^2-7x+9\right)\)

=X⁴-3X³ +6X³-18X²+11X²-33X+6X-18

=(X-3)(X³+6X²+11X+6)

=(X-3)(X+3)(X+1)(X+2)

\(x^4+3x^3-7x^2-27x-18.\)

\(=\left(x^4-9x^2\right)+\left(3x^3-27x\right)+\left(2x^2-18\right)\)

\(=x^2\left(x-3\right)\left(x+3\right)+3x\left(x-3\right)\left(x+3\right)+2\left(x-3\right)\left(x+3\right).\)

\(=\left(x-3\right)\left(x+3\right)\left(x^2+3x+2\right)\)

\(=\left(x-3\right)\left(x+3\right)\left(x^2+x+2x+2\right)\)

\(=\left(x-3\right)\left(x+3\right)\left(x+1\right)\left(x+2\right).\)

\(x^4+3x^3-7x^2-27x-18\)

\(=x^4+2x^3+x^3+2x^2-9x^2-18x-9x-18\)

\(=x^3\left(x+2\right)+x^2\left(x+2\right)-9x\left(x+2\right)-9\left(x+2\right)\)

\(=\left(x+2\right)\left(x^3+x^2-9x-9\right)\)

\(=\left(x+2\right)\left[x^2\left(x+1\right)-9\left(x+1\right)\right]\)

\(=\left(x+2\right)\left(x+1\right)\left(x^2-9\right)\)

\(=\left(x+2\right)\left(x+1\right)\left(x-3\right)\left(x+3\right)\)

a,( x⁴-x³)-(x²-1)

=x³(x-1)-(x-1)(x+1)

=(x³-x-1)(x-1)

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