MathDB
Turkey NMO 2000 1st Round - P26 (Number Theory)

Source:

July 25, 2012

Problem Statement

Let f(x)=x3+7x2+9x+10f(x)=x^3+7x^2+9x+10. Which value of pp satisfies the statement f(a)f(b) (mod p)ab (mod p) f(a) \equiv f(b) \ (\text{mod } p) \Rightarrow a \equiv b \ (\text{mod } p) for every integer a,ba,b?
<spanclass=latexbold>(A)</span> 5<spanclass=latexbold>(B)</span> 7<spanclass=latexbold>(C)</span> 11<spanclass=latexbold>(D)</span> 13<spanclass=latexbold>(E)</span> 17 <span class='latex-bold'>(A)</span>\ 5 \qquad<span class='latex-bold'>(B)</span>\ 7 \qquad<span class='latex-bold'>(C)</span>\ 11 \qquad<span class='latex-bold'>(D)</span>\ 13 \qquad<span class='latex-bold'>(E)</span>\ 17