(a+9)(a-9)(6+x)(6-x)( 1+4b)( 1-4b)(m+3n)(m-3n)(0.5q+ 1 1p)(0.5q- 1 1p)( 13x

+2y)( 13x-2y)(3ap+bq)(3ap-bq)(7 \ 2a+xy)(7 \ 2a-xy)

2

M (m+2n) (11a-3b) (3a-11b) 3 (x +y) (x square +y square +xy)(x square+y square -xy).

3ax(x+y square) (x-y square) (p square+1(p+1) (p-1).

three

S= large circle area-small circle area