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Quadratic Equations
Example 4

Example 4: Quadratic Equation Methods

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

Problem

Sum of roots for 2x2−8x−42=0 is ?\text{Sum of roots for }2x^2-8x-42=0\text{ is }?

1. Recognize Pattern

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

2. Apply Method

2x2+12x+10=0⇒x∈{−1,−5}2x^2+12x+10=0\Rightarrow x\in\left\{-1,-5\right\}

3. Conclude

r1+r2=−ba=4r_1+r_2=-\frac{b}{a}=4

Final answer

r1+r2=−ba=4r_1+r_2=-\frac{b}{a}=4
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