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Perplex
Perplex
Dashboard
Topics
Exponents & LogarithmsRounding & ErrorSequences & SeriesCounting & BinomialsProof and ReasoningComplex NumbersAlgebra Skills
Cartesian plane & linesQuadraticsFunction TheoryTransformations & asymptotesPolynomials
2D & 3D GeometryTrig equations & identitiesVectors
ProbabilityDescriptive StatisticsBivariate StatisticsDistributions & Random Variables
DifferentiationIntegrationDifferential EquationsMaclaurin
Review VideosFormula BookletMy Progress
BlogLanding Page
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Perplex

Polynomials (Lesson 4/4)

Polynomial roots

1 / 12

At this point, you have extensively studied quadratics, which are really polynomials of degree ​2​ (in the same way a square is also a rectangle). You've learned the quadratic formula,

​
x=2a−b±√b2−4ac​​,
​

for the roots of a quadratic, and you've seen how there are no real roots if ​b2−4ac<0. We also learned that these roots were related to factors. If a quadratic has roots ​α​ and ​β, then we can write it in the factored form

​
A(x−α)(x−β).
​

The roots are obvious in this form, as substituting ​x=α​ or ​x=β​ makes the whole expression ​0.


I'm giving you this brief refresher because polynomials work in much the same way. All polynomials have roots and corresponding factors, but the methods for finding them are far harder than for quadratics. However, many of the patterns we've learned about quadratics generalize in useful ways for higher order polynomials.

Polynomials (Lesson 4/4)

Polynomial roots

1 / 12

At this point, you have extensively studied quadratics, which are really polynomials of degree ​2​ (in the same way a square is also a rectangle). You've learned the quadratic formula,

​
x=2a−b±√b2−4ac​​,
​

for the roots of a quadratic, and you've seen how there are no real roots if ​b2−4ac<0. We also learned that these roots were related to factors. If a quadratic has roots ​α​ and ​β, then we can write it in the factored form

​
A(x−α)(x−β).
​

The roots are obvious in this form, as substituting ​x=α​ or ​x=β​ makes the whole expression ​0.


I'm giving you this brief refresher because polynomials work in much the same way. All polynomials have roots and corresponding factors, but the methods for finding them are far harder than for quadratics. However, many of the patterns we've learned about quadratics generalize in useful ways for higher order polynomials.