x3 – 4x2 – 12x + 27

(Nhóm để xuất hiện nhân tử chung)

= (x3 + 27) – (4x2 + 12x)

= (x3 + 33) – (4x2 + 12x)

(nhóm 1 là HĐT, nhóm 2 có 4x là nhân tử chung)

= (x + 3)(x2 – 3x + 9) – 4x(x + 3)

= (x + 3)(x2 – 3x + 9 – 4x)

= (x + 3)(x2 – 7x + 9)

a) (x - y)(x + y + 3).                    b) (x + y - 2xy)(2 + y + 2xy).

c) x 2 (x + l)( x 3  -  x 2  + 2).              d) (x – 1 - y)[ ( x   -   1 ) 2   +   ( x   -   1 ) y   +   y 2 ].

a) x⁶ + y⁶ = (x²)³ + (y²)³

= (x² + y²)(x⁴ - x²y² + y⁴)

b) x⁶ - y⁶

= (x³)² - (y³)²

= (x³ - y³)(x³ + y³)

= (x - y)(x² + xy + y²)(x + y)(x² - xy + y²)

\(a,4x^2-25-\left(2x-5\right)\left(2x+7\right)\)

\(=\left(2x-5\right)\left(2x+5\right)-\left(2x-5\right)\left(2x+7\right)\)

\(=\left(2x-5\right)\left(2x+5-2x-7\right)\)

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

\(b,x^3+27+\left(x+3\right)\left(x-9\right)\)

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

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

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

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

=.= hok tốt!!

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

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

\(a,=-\left(x-1\right)^3\left[=\left(1-x\right)^3\right]\\ b,=\left(1-x\right)^3\)

1+1 = 1+1

2

a) x3 + 3x2 – 3x – 9

= (x3 + 3x2) - (3x + 9)

= x2(x + 3) - 3(x + 3)

= (x + 3)(x2 - 3)

= (x + 3)(x + √3)(x - √3)

x 6 - y 6 = x 3 2 - y 3 2 = x 3 + y 3 x 3 - y 3 = x + y x 2 - x y + y x - y x 2 + x y + y 2

a: \(10x^3-90x^5\)

\(=10x^3\cdot1-10x^3\cdot9x^2\)

\(=10x^3\left(1-9x^2\right)=10x^3\left(1-3x\right)\left(1+3x\right)\)

b: \(3a^2-6a^2b+5a-10ab\)

=3a^2(1-2b)+5a(1-2b)

=(1-2b)(3a^2+5a)

=a(3a+5)(1-2b)

c: \(7a^3-28a^2+28a\)

\(=7a\left(a^2-4a+4\right)\)

\(=7a\left(a-2\right)^2\)

d: \(45a^3-30a^2+5a-500\)

\(=5\left(9a^3-6a^2+5a-100\right)\)

e:Sửa đề: \(a^2b-49b+14b^2-b^3\)

\(=b\left(a^2-49+14b-b^2\right)\)

\(=b\left\lbrack a^2-\left(b-7\right)^2\right\rbrack\)

=b(a-b+7)(a+b-7)

f: \(x^4+4\)

\(=x^4+4x^2+4-4x^2\)

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