2x的4次方-8分之1
=2(x^4-1/16)
=2(x²+1/4)(x²-1/4)
=2(x²+1/4)(x-1/2)(x+1/2)
(2x+y)平方-6(2x+y)+9
=(2x+y-3)²
25(x+y)平方-9(x-y)平方
=[5(x+y)+3(x-y)][5(x+y)-3(x-y)]
=(8x-2y)(2x+8y)
=4(4x-y)(x+4y)
解:①2x^4-1/8=2(x^4-1/16)=2(x^2+1/4)(x^2-1/4))=2(x-1/2)(x+1/2)(x^2+1/4)
②(2x+y)^2-6(2x+y)+9 =(2x+y-3)^2
③25(x+y)^2-9(x-y)^2
=(5x+5y)^2-(3x-3y)^2
=(5x+5y+3x-3y)〔5x+5y-(3x-3y)〕
=(8x-2y)(5x+5y-3x+3y)
=2(4x-y)(2x+8y)
=4(4x-y)(x+4y)