谁能帮我解决数学难题啊因式分解1.1/3X^2-4/3X-7 2.-a+11/2ab-6b^23.(x+y)^2-4(x+y)-12 4.(2x-y)^2-4x+2y5.-6m^2+7mn-5/3n^2 6.(x^2+5x-2)(x^2+5x)-8

1原式=1/3(x^2-4x-21)=1/3(x-7)(x+3)
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2原式=-1/2(2a^2-11ab+12b^2)=-1/2(2a-3b)(a-4b)
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3原式=(x+y-6)(x+y+2)
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4原式=(2x-y)^2-2(2x-4)=(2x-y)(2x-y-2)
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5原式=-1/3(18m^2-21mn+5n^2)-1/3(3m-n)(6m-5)
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6原式=(x^2+5x)^2-2(x^2+5x)-8=(x^2+5x-4)(x^2+5x+2)

1/3X^2-4/3X-7 =1/3(x-7)(x+3)
-a+11/2ab-6b^2 =-1/2(2a-3b)(a-4b)
(x+y)^2-4(x+y)-12 =(x+y-6)(x+y+2)
(2x-y)^2-4x+2y =(2x-y)(2x-y-2)
-6m^2+7mn-5/3n^2 =-1/3(3m-n)(6m-5)
(x^2+5x-2)(x^2+5x)-8 =(x^2+5x-4)(x^2+5x+2)