若7a-8b=5.求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)的值

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若7a-8b=5.求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)的值
若7a-8b=5.求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)的值

若7a-8b=5.求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)的值
(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=(7a-8b)(3a-4b+11a-12b)
=(7a-8b)(14a-16b)
=2(7a-8b)²
=2×5²
=50

我愧对数学老师

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=(3a-4b)(7a-8b)+(11a-12b)(7a-8b)
=（7a-8b）（3a-4b+11a-12b）
=（7a-8b）（14a-16b）
=2（7a-8b）²
=2×5²
=50

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=5(3a-4b)+5(11a-12b)
=15a-20b+55a-60b
=70a-80b
=10(7a-8b)
=50

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=(3a-4b)(7a-8b)+(11a-12b)(7a-8b)
=(7a-8b)(3a+11a-4b-12b)
=(7a-8b)(14a-16b)
=(7a-8b)×2×(7a-8b)
=5×2×5=50

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)=﹙7a-8b﹚﹙3a-4b+11a-12b﹚=5﹙14a-16b﹚=5×2×5=50

原式=(3a-4b)*5-(11a-12b)(-5)=5(3a-4b+11a-12b)=5(14a-16b)=10(7a-8b)=50

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=(3a-4b+11a-12b)(7a-8b)
=(14a-16b)(7a-8b)=2(7a-8b)(7a-8b)=2*5*5=50

先提出来-（7a-8b) :-(7a-8b)*[(3a-4b)+(11a-12b)]
=-5*(3a-4b+11a-12b)
=-5*(14a-16b)
=-5*2*5
=-50
应该是这样

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=（7a-8b)x(14a-16b)
=2x(7a-8b)x(7a-8b)
=2x5x5
=50

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=(7a-8b)(3a-4b+11a-12b)
=5(14a-16b)
=5*10
=50

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