(2x3-1)2= (2x3)2+2[(2x3)∙(-1)]+(-1)2=4x3∙2-2x3+1= 4x6-4x3+1
(3x-xm)2= (3x)2+2[(3x)∙(-xm)]+(-xm)2= 9x2-6x∙xm+x2m=9x2-6xm+1+x2m
(2x3-1)2= (2x3)2+2[(2x3)∙(-1)]+(-1)2=4x3∙2-2x3+1= 4x6-4x3+1
(3x-xm)2= (3x)2+2[(3x)∙(-xm)]+(-xm)2= 9x2-6x∙xm+x2m=9x2-6xm+1+x2m