Skip to content
Factoring Polynomials
Example 6

Example 6: Factoring Quadratics

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

Problem

Larger root of x24x5=0 is ?\text{Larger root of }x^2-4x-5=0\text{ is }?

1. Recognize Pattern

x2+bx+c=(xr1)(xr2),  r1+r2=b,  r1r2=cx^2+bx+c=(x-r_1)(x-r_2),\;r_1+r_2=-b,\;r_1r_2=c

2. Apply Method

x2x20=(x4)(x5)x^2-x-20=(x--4)(x-5)

3. Conclude

x{5,1}x\in\left\{5,-1\right\}

Final answer

x{5,1}x\in\left\{5,-1\right\}