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Recall the Conjugate Root Theorem.
14+sqrt(2), 6i
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Irrational Conjugate Root Theorem |
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If P(x) is a polynomial with rational coefficients, then any irrational roots of P(x)=0 occur in conjugate pairs. |
The above statement tell us that if a + sqrt(b) is an irrational root, then a - sqrt(b) is also a root. Let's use this to find an additional irrational root.
| Hypotheses | Conclusion |
|---|---|
| P(x) has rational coefficients | 14+sqrt(2) is also a root of P(x) |
| 14-sqrt(2) is an irrational root of P(x)=0 |
To find the remaining root, let's recall the Conjugate Root Theorem.
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Conjugate Root Theorem |
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If P(x) is a polynomial with real coefficients, then any complex roots of P(x)=0 occur in conjugate pairs. |
This means that if a + bi is a complex root, then a - bi is also a root. Let's now use this to find the other complex root.
| Hypotheses | Conclusion |
|---|---|
| P(x) has rational, real coefficients | 0+6i=6i is also a root of P(x) |
| - 6i=0-6i is a complex root of P(x) |
The two additional roots that we can know for certain using the Complex Conjugate Root Theorem are 14+sqrt(2) and 6i.