.(2a+3b-4c)^2-(2a-3b+4c)^2

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.(2a+3b-4c)^2-(2a-3b+4c)^2.(2a+3b-4c)^2-(2a-3b+4c)^2.(2a+3b-4c)^2-(2a-3b+4c)^2.(2a+3b-4c)^2-(2a-3b+4

.(2a+3b-4c)^2-(2a-3b+4c)^2
.(2a+3b-4c)^2-(2a-3b+4c)^2

.(2a+3b-4c)^2-(2a-3b+4c)^2
.(2a+3b-4c)^2-(2a-3b+4c)^2
=(2a+3b-4c+2a-3b+4c)(2a+3b-4c-2a+3b-4c)
=4a(6b-8c)
=8a(3b-4c)
=24ab-32ac

拿50分调人胃口哪?题呢?没写完吧

(2a+3b-4c)^2-(2a-3b+4c)^2
=[(2a+3b-4c)+(2a-3b+4c)][(2a+3b-4c)-(2a-3b+4c)]
=4a(6b-8c)
=8a(3b-4c)
=24ab-32ac
平方差公式的运用

(2a+3b-4c)^2-(2a-3b+4c)^2
=[2a+(3b-4c)]^2-[2a-(3b-4c)]^2
=[2a+(3b-4c)+2a-(3b-4c)][2a+(3b-4c)-2a+(3b-4c)]
=(2a+3b-4c+2a-3b+4c)(2a+3b-4c-2a+3b-4c)
=4a(6b-8c)
=24ab-32ac

(2a+3b-4c)^2-(2a-3b+4c)^2
=(2a+3b-4c+2a-3b+4c)(2a+3b-4c-2a+3b-4c)
=8a(3b-4c)