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Quadratic Equations
Example 2

Example 2: Quadratic Equation Methods

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

Problem

Sum of roots for 3x2−39x+126=0 is ?\text{Sum of roots for }3x^2-39x+126=0\text{ is }?

1. Recognize Pattern

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

2. Apply Method

2x2−18x+36=0⇒x∈{6,3}2x^2-18x+36=0\Rightarrow x\in\left\{6,3\right\}

3. Conclude

r1+r2=−ba=13r_1+r_2=-\frac{b}{a}=13

Final answer

r1+r2=−ba=13r_1+r_2=-\frac{b}{a}=13
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