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

=(x-5)(x-4)

\(=x^2-4x-5x+20=\left(x-4\right)\left(x-5\right)\)

\(x^2-9x+20=\left(x^2-4x\right)-\left(5x-20\right)=x\left(x-4\right)-5\left(x-4\right)=\left(x-4\right)\left(x-5\right)\)

A=\(x^2-9x\)

\(=x\cdot x-x\cdot9\)

=x(x-9)

\(9x^2-4\left(x-1\right)^2\)

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

\(=\left[3x+2x-2\right]\left[3x-2x+2\right]\)

\(=\left(5x-2\right)\left(x+2\right)\)

Trí làm đúng rồi nha

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

\(=\left(x^2+2x\right)^2+9\left(x^2+2x\right)+20\)

\(=\left(x^2+2x+4\right)\left(x^2+2x+5\right)\)

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

\(-x^3+9x^2-27x+27\)

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

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

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

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

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

       \(x^3-9x^2+14x\)

= \(x^3-7x^2-2x^2+14x\)

= \(x^2.\left(x-7\right)-2x.\left(x-7\right)\)

= \(\left(x-7\right).\left(x^2-2x\right)\)

= \(\left(x-7\right).\left(x-2\right).x\)

\(x^3-9x^2+14x\)

\(=x\left(x^2-9x+14\right)\)

\(=x\left(x^2-7x-2x+14\right)\)

\(=x\left[x\left(x-7\right)-2\left(x-7\right)\right]\)

\(=x\left(x-2\right)\left(x-7\right)\)

khó quá tui ko biết làm..

k cho tui nha

thanks

x² + 3x + 6x + 18

= x(x + 3) + 6(x + 3)

= (x + 6)(x + 3)

dễ ẹc!!!!!!!!

\(x^2+9x+18\)

\(=x^2+6x+3x+18\)

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

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

a) x² - 9x + 8

= x² - 9x - 1 + 9

= (x² - 1) + (-9x + 9)

= (x + 1) (x - 1) - 9(x - 1)

= (x - 1) (x + 1 - 9)

= (x - 1) (x - 8)

b) x² + 6x + 8

= x² + 2x + 4x + 8

= (x² + 2x) + (4x + 8)

= x(x + 2) + 4(x + 2)

= (x + 2) (x + 4)

ok mk nha!!! 6476775758766925353464565645645765687687676976924563464554

a) x² - 9x + 8

= x² - 9x - 1 + 9

= (x² - 1) + (-9x + 9)

= (x + 1) (x - 1) - 9(x - 1)

= (x - 1) (x + 1 - 9)

= (x - 1) (x - 8)

b) x² + 6x + 8

= x² + 2x + 4x + 8

= (x² + 2x) + (4x + 8)

= x(x + 2) + 4(x + 2)

= (x + 2) (x + 4)