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1981 AMC 12 Question 28

AMC12 · 1981 AMC 12

Question 28

Consider the set of all equations $x^3+a_2x^2+a_1x+a_0=0,$ where $a_2,$ $a_1,$ $a_0$ are real constants and $|a_i|\le2$ for $i=0,$ $1,$ $2.$ Let $r$ be the largest positive real number which satisfies at least one of these equations. Then
  1. $1\le r\lt\frac32$
  2. $\frac32\le r\lt2$
  3. $2\le r\lt\frac52$
  4. $\frac52\le r\lt3$
  5. $3\le r\lt\frac72$