Fundamental Theorem of Algebra Flashcards
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Questions and Answers

What is the total number of roots of the polynomial function f(x) = 3x^6 + 2x^5 + x^4 - 2x^3?

6

What is the total number of roots of the polynomial function g(x) = 5x - 12x^2 + 3?

2

What is the total number of roots of the polynomial function f(x) = (3x^4 + 1)^2?

8

What is the total number of roots of the polynomial function g(x) = (x - 5)^2 + 2x^3?

<p>3</p> Signup and view all the answers

What is the total number of roots of the polynomial function f(x) = (x + 1)(x - 3)(x - 4)?

<p>3</p> Signup and view all the answers

What is the total number of roots of the polynomial function f(x) = (x - 6)^2(x + 2)^2?

<p>4</p> Signup and view all the answers

What is the total number of roots of the polynomial function f(x) = (x + 5)^3(x - 9)(x + 1)?

<p>5</p> Signup and view all the answers

What is the total number of roots of the polynomial function f(x) = (x + 2)(x - 1)[x - (4 + 3i)][x - (4 - 3i)]?

<p>4</p> Signup and view all the answers

What are the root(s) of f(x) = (x - 6)^2(x + 2)^2?

<p>6 with multiplicity 2, -2 with multiplicity 2</p> Signup and view all the answers

What are the root(s) of f(x) = (x + 5)^3(x - 9)^2(x + 1)?

<p>-5 with multiplicity 3, 9 with multiplicity 2, -1 with multiplicity 1</p> Signup and view all the answers

What is the number of x-intercepts that appear on the graph of the function f(x) = (x + 1)(x - 3)(x - 4)?

<p>3</p> Signup and view all the answers

What is the number of x-intercepts that appear on the graph of the function f(x) = (x - 6)^2(x + 2)^2?

<p>2</p> Signup and view all the answers

What is the number of x-intercepts that appear on the graph of the function f(x) = (x + 5)^3(x - 9)(x + 1)?

<p>3</p> Signup and view all the answers

What is the number of x-intercepts that appear on the graph of the function f(x) = (x + 2)(x - 1)[x - (4 + 3i)][x - (4 - 3i)]?

<p>2</p> Signup and view all the answers

At x = 2, the graph of f(x) = (x − 2)^3(x + 6)^2(x + 12) _______ the x-axis. At x = −6, the graph _______ the x-axis. At x = −12, the graph _______ the x-axis.

<p>crosses; touches; crosses</p> Signup and view all the answers

At x = −4, the graph of g(x) = (x + 4)^4(x − 9) ______ the x-axis. At x = 9, the graph ______ the x-axis.

<p>touches; crosses</p> Signup and view all the answers

If you know a root of a function is -2 + √3i, then _____. (Choose one)

<p>-2 - √3i is a known root.</p> Signup and view all the answers

Three roots of the polynomial function f(x) = x^5 - 8x^4 + 21x^3 - 12x^2 - 22x + 20 are -1, 1, and 3 + i. Which of the following describes the number and nature of all the roots of this function? (Choose one)

<p>f(x) has three real roots and two imaginary roots.</p> Signup and view all the answers

Identify all of the root(s) of g(x) = (x^2 + 3x - 4)(x^2 - 4x + 29).

<p>1, -4, 2 + 5i, 2 - 5i</p> Signup and view all the answers

Using the fundamental theorem of algebra, what is the number and nature of the remaining root(s) for the polynomial function f(x) = x^3 - 7x - 6 if two roots are -2 and 3?

<p>The final root must be real.</p> Signup and view all the answers

Study Notes

Fundamental Theorem of Algebra

  • The theorem states that a polynomial of degree ( n ) has exactly ( n ) roots, counting multiplicities and including complex roots.

Total Number of Roots

  • For ( f(x) = 3x^6 + 2x^5 + x^4 - 2x^3 ): Total roots = 6
  • For ( g(x) = 5x - 12x^2 + 3 ): Total roots = 2
  • For ( f(x) = (3x^4 + 1)^2 ): Total roots = 8
  • For ( g(x) = (x - 5)^2 + 2x^3 ): Total roots = 3
  • For polynomial ( f(x) = (x + 1)(x - 3)(x - 4) ): Total roots = 3
  • For ( f(x) = (x - 6)^2(x + 2)^2 ): Total roots = 4
  • For ( f(x) = (x + 5)^3(x - 9)(x + 1) ): Total roots = 5
  • For ( f(x) = (x + 2)(x - 1)[x - (4 + 3i)][x - (4 - 3i)] ): Total roots = 4

Roots with Multiplicities

  • For ( f(x) = (x - 6)^2(x + 2)^2 ):
    • Roots are ( 6 ) (multiplicity 2) and ( -2 ) (multiplicity 2).
  • For ( f(x) = (x + 5)^3(x - 9)^2(x + 1) ):
    • Roots are ( -5 ) (multiplicity 3), ( 9 ) (multiplicity 2), and ( -1 ) (multiplicity 1).

Number of x-Intercepts

  • For ( f(x) = (x + 1)(x - 3)(x - 4) ): x-intercepts = 3
  • For ( f(x) = (x - 6)^2(x + 2)^2 ): x-intercepts = 2
  • For ( f(x) = (x + 5)^3(x - 9)(x + 1) ): x-intercepts = 3
  • For ( f(x) = (x + 2)(x - 1)[x - (4 + 3i)][x - (4 - 3i)] ): x-intercepts = 2

Graph Behavior at Roots

  • For ( f(x) = (x - 2)^3(x + 6)^2(x + 12) ):
    • At ( x = 2 ), graph crosses x-axis.
    • At ( x = -6 ), graph touches x-axis.
    • At ( x = -12 ), graph crosses x-axis.
  • For ( g(x) = (x + 4)^4(x - 9) ):
    • At ( x = -4 ), graph touches x-axis.
    • At ( x = 9 ), graph crosses x-axis.

Complex Roots

  • If a root is ( -2 + \sqrt{3}i ), then ( -2 - \sqrt{3}i ) is a known root due to the complex conjugate theorem.

Roots of Specific Polynomials

  • For ( f(x) = x^5 - 8x^4 + 21x^3 - 12x^2 - 22x + 20 ):
    • Known roots are ( -1, 1, 3 + i ).
    • Nature of roots: 3 real roots and 2 imaginary roots.
  • For ( g(x) = (x^2 + 3x - 4)(x^2 - 4x + 29) ):
    • Roots include ( 1, -4, 2 + 5i, 2 - 5i ).

Remaining Roots Using Theorems

  • For ( f(x) = x^3 - 7x - 6 ) with known roots ( -2 ) and ( 3 ):
    • Degree of polynomial = 3, implying 3 total roots.
    • With two known roots, one root remains and must be real due to complex conjugate theorem for imaginary pairs.

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Test your understanding of the Fundamental Theorem of Algebra with these flashcards. Each card challenges you to determine the total number of roots of various polynomial functions. Perfect for reviewing key concepts in algebra!

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