9(x+2y)的2次方-25(x-2y)的2次方=?(8x-4y)(-2x+16y) =-8(2x-y)(x-8y)这一

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9(x+2y)的2次方-25(x-2y)的2次方=?(8x-4y)(-2x+16y) =-8(2x-y)(x-8y)这一步怎么算过去的

9(x+2y)的2次方-25(x-2y)的2次方
=[3(x+2y)+5(x-2y)][3(x+2y)-5(x-2y)]
=(3x+6y+5x-10y)(3x+6y-5x+10y)
=(8x-4y)(16y-2x)
=8(2x-y)(8y-x)
=-8(2x-y)(x-8y)
再问：为什么(8x-4y)(16y-2x)=8(2x-y)(8y-x)
再答： (8x-4y)(16y-2x) =4(2x-y)*2(8y-x) =8(2x-y)(8y-x) =-8(2x-y)(x-8y) 把常数的公因数提取出来

9(x+2y)的2次方-25(x-2y)的2次方=?(8x-4y)(-2x+16y) =-8(2x-y)(x-8y)这一【2(x-y)的3次方-8(x-y)的2次方(x+y)+6y(x-y)的平方】/2(x-y)的平方=? (x+y)的2次方+8(x+y)+16 因式分解 {(z+y)(x-y)-(x-y)的2次方+2y(x-y)}除以4y y(x+y)+(x+y)(x-y)-x的2次方,其中X=-2,y=2分之一. 2x+3y=4,4的x次方×8的y次方=? (x—y)的2次方×（x—y)的5次方×（y-x)=() 已知x-y=2,x的2次方-y的2次方=8,求x,y的值若2的x次方=8的y+1次方,81的y次方=9的x-5次方,则x的y次方=? [2(x一y)的3次方一8(x一y)的2次方(x+y)+6y(x一y)的2次方]÷2(x一y)的2次方初一,算术题,[2(x一y)的3次方一8(x一y)的2次方(x+y)+6y(x一y)的2次方]÷2(x一y)的2次方 (x-y)的2次方-2(x-y)+(x-y)-5(x-y)