2x(x-y)+3y(x-y)=(x-y)*(2x+3y)
4a+4b+bx+ax=4(a+b)+x×(b+a)=(a+b)*(4+x)
(1+3m) (1-3x)=1-3x+3m-3m×3x=1-3x+3m-9mx
2x(x-y)+3y(x-y)=(x-y)*(2x+3y)
4a+4b+bx+ax=4(a+b)+x×(b+a)=(a+b)*(4+x)
(1+3m) (1-3x)=1-3x+3m-3m×3x=1-3x+3m-9mx