AP PrecalculusUnit 1A - Polynomial and Rational Functions

1.5A Polynomial Functions and Complex Zeros

Polynomial functions can have complex zeros when their solutions involve imaginary numbers. Complex zeros always occur in conjugate pairs if the polynomial has real coefficients. This means if a + bi is a zero, then a - bi is also a zero. Understanding complex zeros is crucial for fully solving polynomial equations and for understanding the nature of polynomials.
1.5A Polynomial Functions and Complex Zeros
Polynomial Functions and Complex Zeros

Polynomial Functions and Complex Zeros

Polynomial functions can have complex zeros when their solutions involve imaginary numbers. Complex zeros always occur in conjugate pairs if the polynomial has real coefficients. This means if a + bi is a zero, then a - bi is also a zero. Understanding complex zeros is crucial for fully solving polynomial equations and for understanding the nature of polynomials.

Examples

Here are ten examples of polynomial functions and their complex zeros:

  1. Function: f(x) = x^2 + 1. Zeros: i, -i
  2. Function: f(x) = x^2 + 4. Zeros: 2i, -2i
  3. Function: f(x) = x^2 + 9. Zeros: 3i, -3i
  4. Function: f(x) = x^2 - 2x + 5. Zeros: 1 + 2i, 1 - 2i
  5. Function: f(x) = x^2 + 6x + 10. Zeros: -3 + i, -3 - i
  6. Function: f(x) = x^2 - 4x + 13. Zeros: 2 + 3i, 2 - 3i
  7. Function: f(x) = x^2 + x + 1. Zeros: -(1/2) + (sqrt(3)/2)i, -(1/2) - (sqrt(3)/2)i
  8. Function: f(x) = x^4 + 4. Zeros: sqrt(2)/2 + (sqrt(2)/2)i, -sqrt(2)/2 + (sqrt(2)/2)i, -sqrt(2)/2 - (sqrt(2)/2)i, sqrt(2)/2 - (sqrt(2)/2)i
  9. Function: f(x) = x^4 - 10x^2 + 9. Zeros: sqrt(3), -sqrt(3), 3i, -3i
  10. Function: f(x) = x^3 - 3x^2 + 4. Zeros: 2, 1 + i, 1 - i

Packet

appc_1.5a_packet.pdf
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Practice Solutions

appc_1.5a_solutions.pdf
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Corrective Assignments

appc_1.5a_ca1.pdf
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appc_1.5a_ca2.pdf
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AP Learning Objectives: 
1.5.A  Identify key characteristics of a polynomial function related to its zeros when suitable factorizations are available or with technology.

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