根据公式(A+B)(A-B)=A^2-B^2
当A=a-2b+3c
B=a+2b-3c时
(a-2b+3c)^2-(a+2b-3c)^2
=[(a-2b+3c)+(a+2b-3c)][(a-2b+3c)-(a+2b-3c)]
=(a-2b+3c+a+2b-3c)(a-2b+3c-a-2b+3c)
=2a(-4b+6c)
=-8ab+12ac
根据公式(A+B)(A-B)=A^2-B^2
当A=a-2b+3c
B=a+2b-3c时
(a-2b+3c)^2-(a+2b-3c)^2
=[(a-2b+3c)+(a+2b-3c)][(a-2b+3c)-(a+2b-3c)]
=(a-2b+3c+a+2b-3c)(a-2b+3c-a-2b+3c)
=2a(-4b+6c)
=-8ab+12ac