If x = -|w|, which of the following must be true?


x =-w

x =w

x2= w

x2= w2

x3= w3

考题讲解

题目分析:

x =−|w|,, 两边同时平方得~$x^2 $~= ~$(−|w|)^2$~,~$x^2=w^2$~;

x=−|w|,得出x-w或者-w. A, B 肯定不对,x=±w, 则~$x^2=w^2$~,~$x^3=± w^3$~;

综上:答案就是D. 

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