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a) x^4 - x^3 - x + 1
= x^3 ( x - 1 ) - ( x- 1 )
= ( x^3 - 1 )(x - 1)
= ( x- 1 )^2 (x^2 + x + 1 )
a)x4-x3-x+1
=x3(x-1)-(x-1)
=(x-1)(x3-1)
=(x-1)(x-1)(x2+x+1)
=(x-1)2(x2+x+1)
b)5x2-4x+20xy-8y
(sai đề)
a)
\(x^5+x^3-x^2-1\)
\(=x^3\left(x^2+1\right)-\left(x^2+1\right)\)
\(=\left(x^2+1\right)\left(x^3-1\right)\)
\(=\left(x^2+1\right)\left(x-1\right)\left(x^2+x+1\right)\)
b)
\(x^2-3x^3-x+3\)
\(=x\left(x-1\right)-3\left(x^3-1\right)\)
\(=x\left(x-1\right)-3\left(x-1\right)\left(x^2+x+1\right)\)
\(=\left(x-1\right)\left(x-3x^2-3x-3\right)\)
\(=\left(x-1\right)\left(-3x^2-2x-3\right)\)
c)
\(x^2-6x+8\)
\(=x^2-2.x.3+9-1\)
\(=\left(x-3\right)^2-1\)
\(=\left(x-3-1\right)\left(x-3+1\right)\)
\(=\left(x-4\right)\left(x-2\right)\)
d)
\(4x^4-4x^2y^2-8y^4\)
\(=\left(2x^2\right)^2-2.\left(2x^2\right)y^2+y^2-9y^4\)
\(=\left(2x^2-y\right)^2-\left(3y^2\right)^2\)
\(=\left(2x^2-y-3y^2\right)\left(2x^2-y+3y^2\right)\)
a,nhóm x*5 với x*3,x*2 và 1: (x*5+ x*3) - (x*2+1) =x*3.(x*2+1)-(x*2+1) =....., câu b nhóm x*2 và -3x*3,x và 3, câu c bang (x-3)*2-1 =..., câu d đat 4 ra.
a) \(x^5+x^3-x^2-1=x^3\left(x^2+1\right)-\left(x^2+1\right)=\left(x^3-1\right)\left(x^2+1\right)\)
b) \(x^2-3x^3-x+3=x\left(x-1\right)-3\left(x^3-1\right)=x\left(x-1\right)-3\left(x-1\right)\left(x^2+x+1\right)=\left(x-1\right)\left[\left(x-3\right)-\left(x^2+x+1\right)\right]=\left(x-1\right)\left(-x^2-4\right)\)c) \(x^2-6x+8=x^2-6x+9-1=\left(x-3\right)^2-1=\left(x-2\right)\left(x-4\right)\)
d) \(4x^4+4x^2y^2-8y^4=4x^4+4x^2y^2+y^4-9y^4=\left(2x^2+y^2\right)^2-9y^4=\left(2x^2+4y^2\right)\left(2x^2-2y^2\right)=2\left(x^2+2y^2\right)2\left(x^2-y^2\right)=4\left(x^2+2y^2\right)\left(x+y\right)\left(x-y\right)\)
\(A=\left(x^2+x\right)^2-14\left(x^2+x\right)+24\)
Đặt \(x^2+x=t\), ta có:
\(A=t^2-14t+24\)
\(=t^2-2t-12t+24\)
\(=t\left(t-2\right)-12\left(t-2\right)\)
\(=\left(t-2\right)\left(t-12\right)\)
\(=\left(x^2+x-2\right)\left(x^2+x-12\right)\)
\(B=\left(x^2+x\right)^2+4x^2+4x-12\)
\(=\left(x^2+x\right)^2+4\left(x^2+x\right)-12\)
Đặt \(x^2+x=t\), ta có:
\(B=t^2+4t-12\)
\(=t^2+6t-2t-12\)
\(=t\left(t+6\right)-2\left(t+6\right)\)
\(=\left(t+6\right)\left(t-2\right)\)
\(=\left(x^2+x+6\right)\left(x^2+x-2\right)\)
\(C=\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)+1\)
\(=\left(x^2+5x+4\right)\left(x^2+5x+6\right)+1\)
Đặt \(x^2+5x+4=t\), ta có:
\(C=t\left(t+2\right)+1\)
\(=t^2+2t+1\)
\(=\left(t+1\right)^2\)
\(=\left(x^2+5x+4+1\right)^2\)
\(=\left(x^2+5x+5\right)^2\)
\(D=\left(x+1\right)\left(x+3\right)\left(x+5\right)\left(x+7\right)+15\)
\(=\left(x^2+8x+7\right)\left(x^2+8x+15\right)+15\)
Đặt \(x^2+8x+7=t\), ta có:
\(D=t\left(t+8\right)+15\)
\(=t^2+8t+15\)
\(=t^2+3t+5t+15\)
\(=t\left(t+3\right)+5\left(t+3\right)\)
\(=\left(t+3\right)\left(t+5\right)\)
\(=\left(x^2+8x+7+3\right)\left(x^2+8x+7+5\right)\)
\(=\left(x^2+8x+10\right)\left(x^2+8x+12\right)\)
\(F=\left(x^2+x+1\right)\left(x^2+x+2\right)-12\)
Đặt \(x^2+x+1=t\), ta có:
\(F=t\left(t+1\right)-12\)
\(=t^2+t-12\)
\(=t^2+4t-3t-12\)
\(=t\left(t+4\right)-3\left(t+4\right)\)
\(=\left(t+4\right)\left(t-3\right)\)
\(=\left(x^2+x+1+4\right)\left(x^2+x+1-3\right)\)
\(=\left(x^2+x+5\right)\left(x^2+x-2\right)\)
\(E=x^4+2x^3+5x^2+4x-12\)
\(=x^4-x^3+3x^3-3x^2+8x^2-8x+12x-12\)
\(=x^3\left(x-1\right)+3x^2\left(x-1\right)+8x\left(x-1\right)+12\left(x-1\right)\)
\(=\left(x-1\right)\left(x^3+3x^2+8x+12\right)\)
\(=\left(x-1\right)\left(x^3+2x^2+x^2+2x+6x+12\right)\)
\(=\left(x-1\right)\left[x^2\left(x+2\right)+x\left(x+2\right)+6\left(x+2\right)\right]\)
\(=\left(x-1\right)\left(x+2\right)\left(x^2+x+6\right)\)
a) \(x^3-x^2-5x+125\)
\(=\left(x+5\right)\left(x^2-5x+25\right)-x\left(x+5\right)\)
\(=\left(x+5\right)\left(x^2-6x+25\right)\)
b) \(5x^2-5xy-3x+3y\)
\(=5x\left(x-y\right)-3\left(x-y\right)\)
\(=\left(x-y\right)\left(5x-3\right)\)
c) \(x^2-2x-4y^2+1\)
\(=\left(x-1\right)^2-4y^2\)
\(=\left(x-2y-1\right)\left(x+2y-1\right)\)
\(1,4x^4+4x^2y^2-8y^4\)
\(=4\left(x^4+x^2y^2-y^4-y^4\right)\)
\(=4\left[\left(x^4-y^4\right)+\left(x^2y^2-y^4\right)\right]\)
\(=4\left[\left(x^2+y^2\right)\left(x^2-y^2\right)+y^2\left(x^2-y^2\right)\right]\)
\(=4\left(x^2-y^2\right)\left(x^2+y^2+y^2\right)\)
\(=4\left(x-y\right)\left(x+y\right)\left(x^2+2y^2\right)\)
\(2,12x^2y-18xy^2-30y^3\)
\(=6y\left(2x^2-3xy-5y^2\right)\)
\(=6y\left[\left(2x^2+2xy\right)-\left(5xy+5y^2\right)\right]\)
\(=6y\left[2x\left(x+y\right)-5y\left(x+y\right)\right]\)
\(=6y\left(x+y\right)\left(2x-5y\right)\)
\(\text{a) }x^5+x^3-x^2-1\\ \\=\left(x^5-x^2\right)+\left(x^3-1\right)\\ \\=x^2\left(x^3-1\right)+\left(x^3-1\right)\\ \\=\left(x^2+1\right)\left(x^3-1\right)\\ \\=\left(x^2+1\right)\left(x-1\right)\left(x^2+x+1\right)\\ \)
\(\text{b) }x^2-x-12\\ \\=x^2-4x+3x-12\\ \\ =\left(x^2-4x\right)+\left(3x-12\right)\\ =x\left(x-4\right)+3\left(x-4\right)\\ \\=\left(x-4\right)\left(x+3\right)\\ \)
a) x5 + x3 - x2 - 1 = ( x5 + x3 ) - ( x2 + 1)
= x3 . ( x2 + 1 ) - ( x2 + 1 )
= ( x2 + 1 ) . ( x3 - 1 )
= ( x2 + 1 ) . ( x - 1 ) . ( x2 + x + 1 )
b) x2 - x - 12 = x2 - 4x + 3x - 12
= x . ( x - 4 ) + 3 . ( x - 4 )
= ( x - 4 ) . ( x + 3 )
c) 4x4 + 4x2y2 - 8y4 = 4x4 - 4x2y2 + 8x2y2 - 8y4
= 4x2 . ( x2 - y2 ) + 8y2 . ( x2 - y2 )
= ( x2 - y2 ) . ( 4x2 + 8y2 )
= 4 . ( x - y ) . ( x + y ) . ( x2 + 2y2 )
\(A=\left(6x-3y\right)+\left(4x^2-4xy+y^2\right)\)
\(=3\left(2x-y\right)+\left(2x-y\right)^2\)
\(=\left(3+2x-y\right)\left(2x-y\right)\)
\(B=9x^2-\left(y^2-4y+4\right)\)
\(=9x^2-\left(y-2\right)^2\)
\(=\left(3x+y-2\right)\left(3x-y+2\right)\)
A = ( 6x - 3y ) + (4x2 - 4xy + y2 )
A = 3.( 2x - y) + [ ( 2x )2 - 2.2.x.y + y2 ]
A = 3.( 2x - y ) + ( 2x - y )2
A = ( 2x - y ).(3 + 2x - y )
B = 9x2 - ( y2 - 4y + 4 )
B = ( 3x )2 - ( y - 2 )2
B = ( 3x - y + 2 ).( 3x + y - 2 )
C = - 25x2 + y2 - 6y + 9
C = ( y2 - 2.3.y + 32 ) - ( 5x )2
C = ( y - 3 )2 - ( 5x )2
C = (y - 3 - 5x ).( y - 3 +5x )
D = x2 - 4x - y2 -- 8y - 12
D = ( x2 - 4x + 4 ) - 4 - y2 - 8y -12
D = ( x - 2.2x + 22 ) - ( y2 + 2.4.y + 42 )
D = ( x - 2 )2 - ( y + 4 )2
D = ( x - 2 + y + 4 ).( x - 2 - y - 4 )
D = ( x + y + 2 ).( x - y - 6 )
a) =x^2+3x+x+3
=x*(x+3)+1*(x+3)
=(x+1)*(x+3)
b) =4x^2-2x+6x-3
=2x*(2x-1)+3*(2x-1)
=(2x-1)*(2x+3)
c) =x^2-4x+3x-12
=x*(x-4)+3*(x-4)
=(x-4)*(x+3)