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题库 / Prep2007E2-DS-182
If m and r are two numbers on a number line, what is the value of r ?
(1) The distance between r and 0 is 3 times the distance between m and 0 .
(2) 12 is halfway between m and r.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
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1. r=3m或-3m
1&2. 当r=3m, (r+m)/2=(3m+m)/2=2m=12, m=6, r=18;
当r=-3m, (r+m)/2=(-3m+m)/2=-m=12, m=-12, r=36.
①r= 18；m= 6
②r= 36；m= -12
m可能为负