a, 6x4-9x3=3x3.(2x-3)
b, x2y2z+xy2z2+x2yz2
=xyz.(xy+yz+xz)
c, 2x(x-3)-(3-x)2
=2x(x-3)-(x-3)2
=(x-3)(2x-x+3)
=(x-3)(x+3)
d,y2(x2+y)-zx2-zy
=y2(x2+y)-z(x2+y)
=(x2+y)(y2-z)
a) 6x4 - 9x3 = 3x3( 2x - 3 )
b) x2y2z + xy2z2 + x2yz2 = xyz ( xy + yz + xz )
c) 2x ( x - 3 )-( 3 - x )2 = 2x ( x - 3 ) - ( x - 3 )2 = ( x - 3 )(2x - 3 + x)
= 3 ( x - 3 )( x - 1 )
d) y2( x2 + y ) - zx2 - zy=y2( x2 + y ) - z( x2 + y )=( x2 + y )( y2 - z )