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Quadratic Equations
Example 8

Example 8: Quadratic Equation Methods

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

Problem

Sum of roots for x2+3x−28=0 is ?\text{Sum of roots for }x^2+3x-28=0\text{ is }?

1. Recognize Pattern

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

2. Apply Method

3x2+6x−45=0⇒x∈{3,−5}3x^2+6x-45=0\Rightarrow x\in\left\{3,-5\right\}

3. Conclude

r1+r2=−ba=−3r_1+r_2=-\frac{b}{a}=-3

Final answer

r1+r2=−ba=−3r_1+r_2=-\frac{b}{a}=-3
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