1.(1-1/2008)(1-1/2007)(1-1/2006)...(1-1/2001)(1-1/1000)
=2007/2008*2006/2007*2005/2006*.*2000/2001*1999/2000
=1999/2008
2.用"84"消毒液配制藥液,對(duì)白色衣物進(jìn)行消毒,要求按1:200的比例進(jìn)行稀釋,現(xiàn)要配制此種藥液4020g,則需"84"消毒液_____g
x/4020=1/200
=>x=20.1
3.已知|x+2|+(y+2)^2=0,求-3(x-2y)^3-2(2x-y)^3的值
絕對(duì)值和平方的值恒為肺腑,只有兩數(shù)都為0時(shí),和才為0
所以x+2=0,y+2=0
x=-2,y-2
-3(x-2y)^3-2(2x-y)^3
=-5(x-2y)^3
=-5*(-2+4)^3
=-5*8
=-40