If one root of quadratic equation with rational coefficients is 3 + root 5, what must the other root be?
Answer and explanation
Correct answer: D. 3 - root 5
- Step 1: For polynomials with rational coefficients, irrational roots occurring in quadratic surds must appear in conjugate pairs. Step 2. Since 3 + root 5 is a root, the other root is 3 - root 5. Answer: 3 - root 5. Why not the others: -3 + root 5 negates rational part; -3 - root 5 negates both parts; root 5 - 3 is -(3 - root 5).
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