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a) \(x^5+x+1=x^5+x^2-x^2+x+1\)
\(=\left(x^5-x^2\right)+\left(x^2+x+1\right)\)
\(=x^2\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x^2\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x^2\left(x-1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left(x^3-x^2+1\right)\)
b) \(x^7+x^2+1=x^7+x^2-x+x+1\)
\(=\left(x^7-x\right)+\left(x^2+x+1\right)\)
\(=x\left(x^6-1\right)+\left(x^2+x+1\right)\)
\(=x\left(x^3+1\right)\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x\left(x^3+1\right)\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x^3+1\right)\left(x-1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left(x^5+x^2+1-x^4-x\right)\)
(Nếu đúng thì k cho mìk với nhé!)
Bài làm
A = 5x( x - 2y ) + 2( 2y - x )2
A = 5x( x - 2y ) + 2( x - 2y )2 [ *chỗ này dùng tính chất ( a - b )2 = ( b - a )2 nha, nếu k hiểu, vào ib ]
A = ( x - 2y )( 5 + 2( x - 2y )
A = ( x - 2y )( 5 + 2x - 4y )
B = ( 4x - 8 )( x2 + 6 ) - ( 4x - 8 )( x + 7 ) + 9( 8 - 4x )
B = ( 4x - 8 )( x2 + 6 ) - ( 4x - 8 )( x + 7 ) - 9( 4x - 8 ) [* Chỗ này mik đổi dấu, nếu thắc mắc vào ib ]
B = ( 4x - 8 )( x2 + 6 - x - 7 - 4x + 8 )
B = ( 4x - 8 )( x2 + 7 - 5x )
B = 4( x - 2 )( x2 + 7 - 5x )
# Học tốt #
\(x^4+4=x^4+4x^2+4-4x^2=\left(x^2+2\right)^2-4x^2=\left(x^2+2x+2\right)\left(x^2-2x+2\right)\)
\(4x^8+1=\left(2x^4\right)^2+1=\left(2x^4\right)^2-2.2x^4+1+2.2.x^4=\left(2x^4+1\right)^2-4x^4\)
\(=\left(2x^4+2x^2+1\right)\left(4x^4-2x^2+1\right)\)
\(x^2-8x-9==x^2+x-9x-9=x\left(x+1\right)-9\left(x+1\right)=\left(x+1\right)\left(x-9\right)\)
\(x^2+14x+48=x^2+6x+8x+48=x\left(x+6\right)+8\left(x+6\right)=\left(x+6\right)\left(x+8\right)\)
a) \(x^4+4=x^4+4x^2+4-4x^2=\left(x^2+2\right)^2-4x^2=\left(x^2+2x+2\right)\left(x^2-2x+2\right)\)
b) \(4x^8+1=\left(2x^4\right)^2+1=\left(2x^4\right)^2-2.2x^4+1+2.2.x^4=\left(2x^4+1\right)^2-4x^4\)
c) \(x^2-8x-9==x^2+x-9x-9=x\left(x+1\right)-9\left(x+1\right)=\left(x+1\right)\left(x-9\right)\)
d) \(x^2+14x+48=x^2+6x+8x+48=x\left(x+6\right)+8\left(x+6\right)=\left(x+6\right)\left(x+8\right)\)
a) \(x^3-x^2-4=x^3-2x^2+x^2-2x+2x-4\)
\(=x^2\left(x-2\right)+x\left(x-2\right)+2\left(x-2\right)\)
\(=\left(x-2\right)\left(x^2+x+2\right)\)
b) \(x^4-64=\left(x^2-8\right)\left(x^2+8\right)\)
c) \(81x^4+4y^4=\left(9x^2+2y^2\right)^2-36x^2y^2=\left(9x^2-6xy+2y^2\right)\left(9x^2+6xy+2y^2\right)\)
d) \(x^7-x^2-1=\left(x^2-x+1\right)\left(x^5+x^4-x^2-x-1\right)\)
\(4x^4-21x^2y^2+y^4\)
\(=\left(4x^4+4x^2y^2+y^4\right)-25x^2y^2\)
\(=\left(2x^2+y^2\right)^2-\left(5xy\right)^2\)
\(=\left(2x^2+y^2-5xy\right)\left(2x^2+y^2+5xy\right)\)
\(a,4x^4-21x^2y^2+y^4=\left(2x^2\right)^2+4x^2y^2+y^4-4x^2y^2-21x^2y^2\)
\(=\left(2x^2+y^2\right)^2-25x^2y^2\)
\(=\left(2x^2+y^2-5xy\right)\left(2x^2+y^2+5xy\right)\)
\(b,x^5-5x^3+4x=x\left(x^4-5x^2+4\right)\)
\(=x\left(x^4-4x^2-x^2+4\right)\)
\(=x\left[x^2\left(x^2-4\right)-\left(x^2-4\right)\right]\)
\(=x\left(x^2-4\right)\left(x^2-1\right)\)
\(=x\left(x-2\right)\left(x+2\right)\left(x-1\right)\left(x+1\right)\)
\(c,x^3+5x^2+3x-9=x^3-x^2+6x^2-6x+9x-9\)
\(=x^2\left(x-1\right)+6x\left(x-1\right)+9\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2+6x+9\right)\)
\(=\left(x-1\right)\left(x^2+3x+3x+9\right)\)
\(=\left(x-1\right)\left[x\left(x+3\right)+3\left(x+3\right)\right]\)
\(=\left(x-1\right)\left(x+3\right)\left(x+3\right)\)
\(=\left(x-1\right)\left(x+3\right)^2\)
\(d,x^{16}+x^8-2=x^{16}+2x^8-x^8-2\)
\(=x^8\left(x^8-1\right)+2\left(x^8-1\right)\)
\(=\left(x^8-1\right)\left(x^8+2\right)\)
\(x^2-y^2\)
\(=x^2+xy-xy-y^2\)
\(=x\left(x+y\right)-y\left(x+y\right)\)
\(=\left(x+y\right)\left(x-y\right)\)