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Quadratic Equations
Example 10

Example 10: Quadratic Equation Methods

Step-by-step worked example for this lesson track.

Problem

Sum of roots for x2+11x+28=0 is ?\text{Sum of roots for }x^2+11x+28=0\text{ is }?

1. Recognize Pattern

x=−b±b2−4ac2ax=\frac{-b\pm\sqrt{b^2-4ac}}{2a}

2. Apply Method

2x2+4x−70=0⇒x∈{−7,5}2x^2+4x-70=0\Rightarrow x\in\left\{-7,5\right\}

3. Conclude

r1+r2=−ba=−11r_1+r_2=-\frac{b}{a}=-11

Final answer

r1+r2=−ba=−11r_1+r_2=-\frac{b}{a}=-11
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