已知X=2007,求(5-2X)^2+(2X+5)(5-2X)的值
(5-2X)^2+(2X+5)(5-2X)
= (5-2X)*[(5-2X)+(5+2X)]
=(5-2X)*10
=(5-2*2007)*10
=(5-4014)*10
=-4009*10
=-40090
(b-a)^3-3(b-a)+2
(b-a)^3-3(b-a)+2
=(b-a)^3-1-3(b-a)+3
=(b-a-1)[(b-a)^2+(b-a)+1]-3(b-a-1)
=(b-a-1)[(b-a)^2+(b-a)+1-3]
=(b-a-1)[(b-a)^2+(b-a)-2]
=(b-a-1)(b-a+2)(b-a-1)
=(b-a-1)^2(b-a+2)