Olympiad workbook
- Exam
- Olympiad workbook
- Subject
- IOQM
- Chapter
- Quadratic Equation
Olympiad workbook · IOQM · Quadratic Equation
Suppose that P is the polynomial of least degree with integer...
Suppose that P is the polynomial of least degree with integer coefficients such that . Find .
Correct answer
40
Step-by-step solution
Let
then
\begin{aligned}
& P(x)=(\sqrt{7}+\sqrt{5})(\sqrt{7}-\sqrt{5})(\sqrt{7}-\sqrt{5}) \quad \text { since } 2=(\sqrt{7}+\sqrt{5})(\sqrt{7}-\sqrt{5}) \\
& =(\sqrt{7}+\sqrt{5})(\sqrt{7}-\sqrt{5})^2 \\
& =(\sqrt{7}+\sqrt{5})\left(24-(\sqrt{7}+\sqrt{5})^2\right) \\
& P(x)=x\left(24-x^2\right) \\
& P(2)=2(24-4) \\
& \hline
\end{aligned}