题目

实数a、b互为相反数，c、d互为倒数，x的绝对值为,，求的值. 答案：【答案】3或9【解析】首先根据a、b互为相反数，c、d互为倒数，可得：a+b=0，cd=1；然后根据x的绝对值为，y2=9，分别求出x、y的值各是多少，再代入x2+（a+b）x- y，求出算式的值是多少即可．解：由题可知： a+b=0,cd=1,|x|=,y2=9则y=3,-3, ∴ ①原式=6+0-1×3=6-3=3∴②原式=6+0-1×(-3)=6+3=9∴式子的值为3或9.A tsunami(海啸) _______ in some southern Asian countries in December, 2004.________ homeless people had to stay in the open air.A. happened; Thousands ofB. has happened; Thousands ofC. happened; Twelve thousands