(2a-b+c)的2次方-(a-2b+c)的2次方

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(2a-b+c)的2次方-(a-2b+c)的2次方

(2a-b+c)的2次方-(a-2b+c)的2次方
=[(2a-b+c)+(a-2b+c)][(2a-b+c)-(a-2b+c)]
=(3a-3b+2c)(a+b)

(2a-b+c)^2 - (a-2b+c)^2
= [(2a-b+c)-(a-2b+c)] * (2a-b+c+a-2b+c)
= (a+b)*(3a-3b+2c)
= 3a^2 - 3ab + 2ac +3ab - 3b^2 + 2bc
= 3a^2 -3b^2 + 2ac + 2bc