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6, x mũ 4 - 4x mũ 3 - 8x mũ 2 + 8x =x (x+2) (x^2-6x+4)
8, x mũ 4 + 2x mũ 3 + x mũ 2 - y mũ 2 = -(y-x^2-x) (y+x^2+x)
10, 4x mũ 2 ( x + y ) -x - y = (2x-1) (2x+1) (y+x)

Trả lời:
a, x4 + 3x3 + x2 + 3x
= ( x4 + 3x3 ) + ( x2 + 3x )
= x3 ( x + 3 ) + x ( x + 3 )
= ( x3 + x ) ( x + 3 )
= x ( x2 + 1 ) ( x + 3 )
b, Sửa đề: x4 - x2 + 8x - 8
= ( x4 - x2 ) + ( 8x - 8 )
= x2 ( x2 - 1 ) + 8 ( x - 1 )
= x2 ( x - 1 ) ( x + 1 ) + 8 ( x - 1 )
= ( x - 1 ) [ x2 ( x + 1 ) + 8 ]
= ( x - 1 ) ( x3 + x2 + 8 )

a, \(x^2-4-3\left(x-2\right)=\left(x-2\right)\left(x+2\right)-3\left(x-2\right)=\left(x-1\right)\left(x-2\right)\)
b, \(x^2-xy+5y-25=\left(x-5\right)\left(x+5\right)-y\left(x-5\right)=\left(x+5-y\right)\left(x-5\right)\)
c, \(x^3+x^2-2x-8=\left(x-2\right)\left(x^2+2x+4\right)+x\left(x-2\right)=\left(x-2\right)\left(x^2+3x+4\right)\)
d, \(x^3-4x^2-8x+8=\left(x+2\right)\left(x^2-2x+4\right)-4x\left(x+2\right)=\left(x^2-6x+4\right)\left(x+2\right)\)
Trả lời:
1, x2 - 4 - 3 ( x - 2 )
= ( x2 - 4 ) - 3 ( x - 2 )
= ( x - 2 ) ( x + 2 ) - 3 ( x - 2 )
= ( x - 2 ) ( x + 2 - 3 )
= ( x - 2 ) ( x - 1 )
2, x2 - xy + 5y - 25
= ( x2 - 25 ) - ( xy - 5y )
= ( x - 5 ) ( x + 5 ) - y ( x - 5 )
= ( x - 5 ) ( x + 5 - y )
3, x3 + x2 - 2x - 8
= ( x3 - 8 ) + ( x2 - 2x )
= ( x - 2 ) ( x2 + 2x + 4 ) + x ( x - 2 )
= ( x - 2 ) ( x2 + 2x + 4 + x )
= ( x - 2 ) ( x2 + 3x + 4 )
4, x3 - 4x2 - 8x + 8
= ( x3 + 8 ) - ( 4x2 + 8x )
= ( x + 2 ) ( x2 - 2x + 4 ) - 4x ( x + 2 )
= ( x + 2 ) ( x2 - 2x + 4 - 4x )
= ( x + 2 ) ( x2 - 6x + 4 )

c, x mũ 2 + 3x - 4 = x^2 + 3 x X -4
c, x mũ 2 + 3x - 18= x^2 + 3xX -18
c, 2x mũ 2 + 3x - 5= 2xX^2 + 3xX -5
c, 3x mũ 2 - 8x + 4= 3 x X^2 - 8 x X + 4
c, 8x mũ 2 + 2x - 3= 8 x X^2 + 2 x X -3

a.\(27x^3+27x^2+9x+1=\left(3x+1\right)^3\)
b.\(x^3-6x^2+12x-8=\left(x-2\right)^3\)
c.\(8x^3+12x^2+6x+1=\left(2x+1\right)^3\)

\(a.3x^2-12xy=3x\left(x-4y\right)\)
\(b.x^2+7x-2\left(x+7\right)=x\left(x+7\right)-2\left(x+7\right)=\left(x-2\right)\left(x+7\right)\)
\(c.8x^3-8x^2+2x=2x\left(4x^2-4+1\right)=2x\left(2x-1\right)^2\)
\(d.x^2-y^2+12y-36=x^2-\left(y-6\right)^2=\left(x-y-6\right)\left(x-y+6\right)\)
Bài làm
a) 3x2 - 12xy
= 3x( x - 4y )
b) x2 + 7x - 2( x + 7 )
= x( x + 7 ) - 2( x + 7 )
= ( x + 7 )( x - 2 )
c) 8x3 - 8x2 + 2x
= 2x( 4x2 - 4x + 1 )
= 2x( 2x - 1 )2
d) x2 - y2 + 12y - 36
= x2 - ( y2 - 12y + 36 )
= x2 - ( y2 - 2.y.6 + 62 )
= x2 - ( y - 6 )2
= ( x - y + 6 )( x + y - 6 )
# Học tốt #
x3+5x2+8x+9
Không có nghiệm nguyên. Giải bằng công thức Cardano, ta được:
\(x_{1} \approx - 3.433 , x_{2 , 3} \approx - 0.783 \pm 1.417 i\)
Vậy:
\(x^{3} + 5 x^{2} + 8 x + 9 = \left(\right. x + 3.433 \left.\right) \left(\right. x^{2} + 2.433 x + 2.621 \left.\right)\)
- Tham khảo nhé chứ tui chx biết là đúng đâu :))-