Ta có : x³ - 7x + 6 

= x³ - x - 6x + 6 

= x(x² - 1) - 6(x - 1)

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

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

= (x - 1) (x² + x - 6) . 

CÁC Ý SAU TƯƠNG TỰ

   x³ - 7x + 6 

= x³ - x - 6x + 6 

= x(x² - 1) - 6(x - 1)

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

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

= (x - 1) (x² + x - 6) . 

1/\(9x^2+6x-575=\left(3x\right)^2+2.3x.1+1-576=\left(3x+1\right)^2-24^2=\left(3x-23\right)\left(3x+25\right)\)

2/\(81x^4+4=81x^4+36x^2+4-36x^2=\left(9x^2+2\right)^2-\left(6x\right)^2\)

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

3/đặt \(t=x^2+8x+7\) thì đa thức cần phân tích:

t(t+8)+15=t²+8t+15=t²+3t+5t+15=t(t+3)+5(t+3)=(t+3)(t+5)=(x²+8x+10)(x²+8x+12)=(x²+8x+10)(x²+2x+6x+12)

=(x²+8x+10)[x(x+2)+6(x+2)]=(x²+8x+10)(x+2)(x+6)

tạm thế này đã, phải đi ăn cơm rồi :v

giúp mình nốt 4,5 nha

Giups hộ cj My :))

4 ) Đặt \(12x^2+11x-1=a\)

\(\left(4x+1\right)\left(12x-1\right)\left(3x+2\right)\left(x+1\right)-4\)

\(=\left(12x^2+11x+2\right)\left(12x^2+11x-1\right)-4\)

\(=\left(a-3\right)a-4=a^2-3a-4=a^2-4a+a-4=a\left(a-4\right)+\left(a-4\right)\)

\(=\left(a+1\right)\left(a-4\right)=\left(12x^2+11x\right)\left(12x^2+11x-5\right)=x\left(12x+11\right)\left(4x+5\right)\left(3x-1\right)\)

a)   x³ -2x² +5x-4

=x³-x²-x²+x+4x-4

=x²(x-1)-x(x-1)+4(x-1)

=(x²-x+4)(x-1)

b) x³-x²+x+3

=x³+x²-2x²-2x+3x+3

=x²(x+1) -2x(x+1)+3(x+1)

=(x²-2x+3)(x+1)

c) 6x³+x²+x+1

=6x³+ 3x²-2x²-x+2x+1

=6x²(x+\(\frac{1}{2}\)) - 2x(x+\(\frac{1}{2}\)) +2(x+\(\frac{1}{2}\))

=(6x²-2x+2) (x+\(\frac{1}{2}\))

=2( 3x²-x+1) (x+\(\frac{1}{2}\))

d)  4x³ + 6x²+4x+1

= 4x³+2x²+4x²+2x+2x+1

= 4x²(x+\(\frac{1}{2}\))+ 4x(x+\(\frac{1}{2}\))+2(x+\(\frac{1}{2}\))

= 2(2x² +2x+1)( x+\(\frac{1}{2}\))

e) x⁶ -9x³+8

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

b.  \(=-x^3+x^2-7x^2+7x-x+1=\left(x-1\right)\left(-x^2-7x-1\right)\)

c.  \(=x^3+2x^2-6x^2-12x+4x+8=\left(x+2\right)\left(x^2-6x+4\right)\)

het thoirui pan oi

\(x^3-4x^2-8x+8\)

\(=x^3+2x^2-6x^2-12x+4x+8\)

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

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

a)x^2-(a+b)x+ab

= x^2 - ax - bx + ab

= (x^2 - ax) - (bx - ab)

= x(x-a) - b(x-a)

= (x-b)(x-a) 

b)7x^3-3xyz-21x^2+9z

= 

c)4x+4y-x^2(x+y)

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

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

= (2-x)(2+x)(x+y)

d) y^2+y-x^2+x

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

= (y-x)(y+x)+ (x+y)

= (y-x+1) (x+y)

e)4x^2-2x-y^2-y

= [(2x)^2 - y^2] - (2x +y)

= (2x-y)(2x+y) - (2x+y)

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

f)9x^2-25y^2-6x+10y

= 

ko biết làm