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lf p(x) = ax^2 + bx+c, then -b/a is equa...

lf `p(x) = ax^2 + bx+c`, then `-b/a` is equal to   :

A

0

B

1

C

product of zeroes

D

sum of zeroes

Text Solution

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The correct Answer is:
To solve the problem, we need to find out what \(-\frac{b}{a}\) represents in the context of the quadratic polynomial \(p(x) = ax^2 + bx + c\). ### Step-by-Step Solution: 1. **Understanding the Polynomial**: We start with the quadratic polynomial given by: \[ p(x) = ax^2 + bx + c \] Here, \(a\), \(b\), and \(c\) are constants. **Hint**: Identify the standard form of a quadratic equation. 2. **Finding the Roots**: The roots (or zeros) of the quadratic polynomial can be found using the quadratic formula: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] This formula gives us two roots, which we can denote as \(\alpha\) and \(\beta\). **Hint**: Recall the quadratic formula and how it relates to the roots of the polynomial. 3. **Sum of the Roots**: The sum of the roots \(\alpha + \beta\) can be calculated as follows: \[ \alpha + \beta = \frac{-b + \sqrt{b^2 - 4ac}}{2a} + \frac{-b - \sqrt{b^2 - 4ac}}{2a} \] When we add these two expressions, the square root terms cancel out: \[ \alpha + \beta = \frac{-b + \sqrt{b^2 - 4ac} - b - \sqrt{b^2 - 4ac}}{2a} = \frac{-2b}{2a} \] **Hint**: Simplify the expression carefully to see how the terms interact. 4. **Final Simplification**: Now, simplifying \(\frac{-2b}{2a}\) gives: \[ \alpha + \beta = \frac{-b}{a} \] Thus, we conclude that: \[ -\frac{b}{a} = \text{Sum of the roots} \] **Hint**: Recognize that the sum of the roots of a quadratic equation is given by \(-\frac{b}{a}\). ### Conclusion: The expression \(-\frac{b}{a}\) is equal to the sum of the roots (or zeros) of the quadratic polynomial \(p(x) = ax^2 + bx + c\).
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