Subjects algebra

Quadratic Roots A90A70

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1. **Problem:** Given that one root of the quadratic equation $x^2 + x + 5 = 0$ is $-5$, determine which of the following statements is NOT true: 1) The other root is $-5$ 2) The sum of the roots is $0$ 3) The discriminant of the quadratic is greater than $0$ 4) The product of the roots is greater than $0$ 2. **Recall the quadratic root properties:** For a quadratic equation $ax^2 + bx + c = 0$, the sum of roots $\alpha + \beta = -\frac{b}{a}$ and the product of roots $\alpha \beta = \frac{c}{a}$. 3. **Apply to the given equation:** Here, $a=1$, $b=1$, $c=5$. Sum of roots $= -\frac{1}{1} = -1$. Product of roots $= \frac{5}{1} = 5$. 4. **Check the given root $-5$:** If one root is $-5$, then the other root $r$ satisfies: Sum: $-5 + r = -1 \implies r = 4$. 5. **Check each statement:** 1) Other root is $-5$? No, it is $4$. 2) Sum of roots is $0$? No, sum is $-1$. 3) Discriminant $\Delta = b^2 - 4ac = 1 - 20 = -19 < 0$, so discriminant is NOT greater than $0$. 4) Product of roots is $5 > 0$, true. 6. **Conclusion:** Statements 1, 2, and 3 are false, but the question asks which is NOT true. The discriminant is less than zero, so statement 3 is false. **Final answer:** The statement that is NOT true is **3) The discriminant of the quadratic is greater than 0**.