Phân tích các đa thức sau thành nhân tử :
a) x - y + 5x - 5y
= ( x + 5x ) - ( y + 5y )
= x . ( 1 + 6 ) - y . ( 1 + 6 )
= ( 1 + 6 ) . ( x - y )
\(a,x-y+5x-5y=\left(x-y\right)+5\left(x-y\right)=6\left(x-y\right)\)
c) 5x2 - 5xy - xy + y2
= 5x ( x - y ) - y ( x - y )
= ( x- y ) ( 5x - y )
\(x-y+5x-5y\)
\(=\left(x-y\right)+5\left(x-y\right)\)
\(=6\left(x-y\right)\)
\(=x^3-4x^2+8x-8\)
\(=x^3-2x^2-2x^2+4x+4x-8\)
\(=x^2\left(x-2\right)-2x\left(x-2\right)+4\left(x-2\right)\)
\(=\left(x^2-2x+4\right)\left(x-2\right)\)
\(5x^2-6xy+y^2\)
\(=5x^2-5xy-xy+y^2\)
\(=5x\left(x-y\right)-y\left(x-y\right)\)
\(=\left(5x-y\right)\left(x-y\right)\)
c) 2x2(x +1) + 4x(x +1); d) 2 x(y - 1) - 2
