Subjects algebra

Polynomial Roots 0C2524

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Polynomial Roots 0C2524


1. **State the problem:** Solve the polynomial equation $$x^7 + 2x^5 + 3x^3 - 2x^2 - 5x - 1 = 0.$$\n\n2. **Formula and approach:** There is no simple closed-form formula for roots of seventh-degree polynomials. We use methods such as the Rational Root Theorem to test possible rational roots, synthetic division to factor, and numerical methods if needed.\n\n3. **Apply the Rational Root Theorem:** Possible rational roots are factors of the constant term $-1$, i.e., $\pm 1$.\n\n4. **Test $x=1$:**\n$$1^7 + 2(1)^5 + 3(1)^3 - 2(1)^2 - 5(1) - 1 = 1 + 2 + 3 - 2 - 5 - 1 = -2 \neq 0.$$\n\n5. **Test $x=-1$:**\n$$(-1)^7 + 2(-1)^5 + 3(-1)^3 - 2(-1)^2 - 5(-1) - 1 = -1 - 2 - 3 - 2 + 5 - 1 = -4 \neq 0.$$\n\n6. **No rational roots found:** Since neither $1$ nor $-1$ is a root, the polynomial has no rational roots.\n\n7. **Conclusion:** The equation must be solved using numerical methods (e.g., Newton-Raphson) or graphing to approximate roots. Exact algebraic solutions are not feasible for this polynomial degree.\n\n**Final answer:** The polynomial equation has no rational roots; numerical approximation methods are required to find its roots.