Name: finding polynomial roots with complex numbers
Uploaded: 2025-11-26T05:43:53.000Z
Duration: 1 min 29 s
Channel: JoVE

複素ゼロは多項式をゼロに等しめる値であり、解に虚数成分が含まれている場合に因数分解中に表示される可能性があります。複素数系は実数を拡張するため、実数係数または複素係数を持つ多項式は、複素零を使用して完全に因数分解できます。この関係は完全因数分解定理で形式化されており、各項の位置を示すために添え字でラベル付けされた係数を持つ次数nの多項式は、線形因子の積として記述でき、各因子は複素ゼロに対応します。これらのゼロの一部は複数回発生する可能性があり、このプロパティは多重度と呼ばれます。たとえば、多重度が 3 のゼロは、多項式の 3 乗に係数を持ち上げます。多重度を数えるとき、零点定理は、 次数n の多項式には正確に n 個のゼロがあり、これは実数、複素数、または繰り返される可能性があると述べています。複素ゼロの実用的な用途は、特定の周波数をブロックするノッチフィルターです。医療機器は、多くの場合、50 Hzまたは60 Hzの電力線からノイズを拾います。これらの周波数に複素ゼロを配置すると、残りの信号を維持しながらノイズが除去されます。

複素零点

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c &#12364;&#22240;&#23376;&#12392;&#12375;&#12390; k &#22238;&#29694;&#12428;&#12427;&#12392;&#12365;&#12289;&#12381;&#12398;&#38646;&#28857;&#12399;&#37325;&#35079;&#24230; k &#12434;&#25345;&#12388;&#12392;&#12356;&#12356;&#12414;&#12377;&#12290;&#37325;&#35079;&#24230;&#12434;&#32771;&#24942;&#12377;&#12427;&#12392;&#12289;n &#27425;&#22810;&#38917;&#24335;&#12399;&#24120;&#12395;&#27491;&#30906;&#12395; n &#20491;&#12398;&#38646;&#28857;&#12434;&#25345;&#12385;&#12414;&#12377;&#12290;&#23455;&#20418;&#25968;&#12434;&#25345;&#12388;&#22810;&#38917;&#24335;&#12398;&#29305;&#21029;&#12394;&#22580;&#21512;&#12289;&#35079;&#32032;&#38646;&#28857;&#12399;&#20849;&#24441;&#12398;&#32068;&#12392;&#12375;&#12390;&#29694;&#12428;&#12414;&#12377;&#12290;&#12377;&#12394;&#12431;&#12385;&#12289;a + bi &#12364;&#38646;&#28857;&#12391;&#12354;&#12428;&#12400; a - bi &#12418;&#38646;&#28857;&#12392;&#12394;&#12426;&#12414;&#12377;&#12290;&#12371;&#12428;&#12395;&#12424;&#12426;&#12289;&#23550;&#24540;&#12377;&#12427;&#20108;&#27425;&#22240;&#23376;&#12290;<figure class='image image-style-align-center' style='display:table;margin-left:auto;margin-right:auto;'><img style='aspect-ratio:300/10;' src='https://cloudfront.jove.com/files/ftp_upload/40058/40058_Equation_2_editor_40058.svg' alt='40058_Equation_2.svg' /></figure>&#12364;&#23455;&#20418;&#25968;&#12434;&#25345;&#12388;&#12371;&#12392;&#12364;&#20445;&#35388;&#12373;&#12428;&#12414;&#12377;&#12290;&#22240;&#25968;&#20998;&#35299;&#12384;&#12369;&#12391;&#12399;&#12377;&#12368;&#12395;&#27714;&#12417;&#12425;&#12428;&#12394;&#12356;&#35079;&#32032;&#38646;&#28857;&#12434;&#35211;&#12388;&#12369;&#12427;&#12383;&#12417;&#12395;&#12399;&#12289;&#20108;&#27425;&#26041;&#31243;&#24335;&#12398;&#20844;&#24335;&#12434;&#29992;&#12356;&#12414;&#12377;&#12290;&#12371;&#12398;&#26041;&#27861;&#12399;&#12289;&#21028;&#21029;&#24335;&#12364;&#36000;&#12398;&#22580;&#21512;&#12395;&#34394;&#25968;&#25104;&#20998;&#12434;&#21547;&#12416;&#27491;&#30906;&#12394;&#35299;&#12434;&#19982;&#12360;&#12289;&#22240;&#25968;&#20998;&#35299;&#12398;&#36942;&#31243;&#12434;&#23436;&#20102;&#12373;&#12379;&#12414;&#12377;&#12290;

&#35079;&#32032;&#38646;&#28857;&#12392;&#12399;&#12289;&#34394;&#25968;&#12289;&#12377;&#12394;&#12431;&#12385; a + bi ...

Education

JoVE Core

Math Fundamentals

数学の基礎

Unit

ユニット

Polynomial and Rational Functions

多項式関数と有理関数

KEY TERMS AND CONCEPTS

主要用語と概念

Complex Zeros

finding polynomial roots with complex numbers

Complex numbers help describe every root of a polynomial equation. A complex number has the form a + bi, where a and b are real numbers and i is the imaginary unit, with i^2 = -1. A complex zero is any value that makes P(x) = 0 for a polynomial P(x).

The complex number system includes the real numbers, so it gives a complete way to study polynomial roots. Every polynomial of degree n  1 can be written as a product of n linear factors over the complex numbers. In that factorization, each c_i is a complex zero of P(x), and a is the leading coefficient. These zeros can be real or nonreal complex values.

Multiplicity is also important when you work with polynomial roots. If a zero c appears k times as a factor in the complete factorization, then it has multiplicity k. When multiplicities are counted, a polynomial of degree n has exactly n zeros.

Polynomials with real coefficients have a special pattern. If a + bi is a zero, then a - bi must also be a zero. These conjugate pairs create a quadratic factor with real coefficients. When a zero is not easy to find by factoring, the quadratic formula can be used. If the discriminant is negative, the formula gives exact solutions with imaginary parts and helps finish the factorization.

Finding Polynomial Roots With Complex Numbers

finding-polynomial-roots-with-complex-numbers

quadratic models

Quadratic Motion and Parabolas

Quadratic models describe relationships where the rate of change changes at a constant rate. In math and science, this often shows up as a curved pattern called a parabola. These models help explain how a system changes over time or under a set force. A common example is the vertical motion of an object moving under gravity, such as a ball thrown into the air. The object rises to a maximum height and then falls back down. Gravity slows the ascent and speeds up the descent, which creates the...

introduction to polynomial functions

Polynomial Graphs, Zeros, and Degree

Polynomial functions are an important part of algebra and calculus. They are made from variables and constants combined by addition, subtraction, and multiplication. The variable is raised to a nonnegative integer exponent. A general polynomial function of degree n has a leading term aₙxⁿ, where aₙ is not equal to 0. The coefficient aₙ is the leading coefficient, and a₀ is the constant term. Polynomials are grouped by degree. A constant function has degree zero, a linear function has degree...

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Polynomial Division: Quotient and Remainder

Polynomial division breaks a polynomial into a quotient and a remainder. It works like numerical division, but the dividend is a polynomial and the divisor is an algebraic expression. The result shows how much of the divisor fits into the dividend and what is left over. The first step is to write both polynomials in standard form, with terms in descending powers of the variable. Then divide the leading term of the dividend by the leading term of the divisor. That first result becomes the first...

synthetic disvision of polynomials

Using Synthetic Division to Find Factors

Synthetic division is a fast way to divide a polynomial by a linear binomial of the form x - c, where c is a real number. It gives a shorter method than polynomial long division and is useful for checking values and finding factors. The setup starts with the coefficients of the polynomial written in descending order of powers. If a term is missing, a zero must be used to keep the columns lined up. The constant c from the divisor x - c is placed to the left of the synthetic division table. The...

real zeros of polynomials

Finding Polynomial X-Intercepts

Polynomials can be analyzed by finding their real zeros, which are the values of x that make the polynomial equal to zero. These points are also the x-intercepts of the graph. Understanding them helps students see where a polynomial crosses the x-axis. The Rational Zeros Theorem gives a list of possible rational solutions for a polynomial with integer coefficients. If f(x)=anx^n+...+a0, then every rational zero has the form p/q. In that form, p divides the constant term a0 and q divides the...

fundamental theorem of algebra

Polynomial Roots in Complex Numbers

Polynomial roots in complex numbers are a key result in algebra. The Fundamental Theorem of Algebra says that every non-constant polynomial with complex coefficients has at least one complex zero. For a polynomial of degree n, where n is at least 1 and the leading coefficient a n is not 0, there is at least one solution in the complex number system. This result also applies to polynomials with real coefficients, because the real numbers are a subset of the complex numbers. The Complete...

complex zeros

Complex numbers help describe every root of a polynomial equation. A complex number has the form a + bi, where a and b are real numbers and i is the imaginary unit, with i^2 = -1. A complex zero is any value that makes P(x) = 0 for a polynomial P(x). The complex number system includes the real numbers, so it gives a complete way to study polynomial roots. Every polynomial of degree n  1 can be written as a product of n linear factors over the complex numbers. In that factorization, each c_i...

asymptotes in rational functions

Graphing Rational Functions with Asymptotes

Rational functions are quotients of two polynomials, with the denominator Q(x) not equal to zero. Their graphs often include asymptotes, which are lines the graph gets close to but does not touch. These lines help show how the function behaves near certain input values and at large values of x. A vertical asymptote appears when the denominator is zero and the numerator is not zero. At those x-values, the function is undefined. To find a vertical asymptote, solve Q(x) = 0. For example, a...

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Linear and nonlinear inequalities help describe variable relationships and the ranges that satisfy a condition. A linear inequality uses variables raised only to the first power. Its graph is a straight line that divides the coordinate plane into two regions. One region satisfies the inequality, and the other does not. Nonlinear inequalities use variables raised to powers greater than one. These include quadratic inequalities and higher-degree polynomial inequalities. Their graphs are curved,...

application of nonlinear inequalities

Solving Nonlinear Inequalities on a Number Line

Nonlinear inequalities can be solved by checking where an expression is positive or negative on a number line. These inequalities often include squares, products, or variables in the denominator, so they do not follow the same simple pattern as linear inequalities. The first step is to rewrite the inequality so that zero is on one side. After rewriting, factor the expression if possible. Factoring helps you find the key values where the expression equals zero. In one example, the values 3 and...

key terms and concepts

Learn how complex numbers, multiplicity, conjugate pairs, and the quadratic formula help find every polynomial root, including imaginary ones.

Finding Polynomial Roots With Complex Numbers | JoVE K12

The JoVE Math Fundamentals collection is designed to build a deep and comprehensive understanding of essential mathematics. Covering the foundations of algebra, geometry, trigonometry, and analytic reasoning, this course establishes a strong base for future studies. The collection connects core mathematical concepts with real-world practice, equipping learners to solve complex problems, master problem-solving skills, and apply abstract ideas.

math fundamentals

Finding Polynomial Roots With Complex Numbers

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