Mathematics (2019) Grade(s): 09-12 - Precalculus

MA19.PRE.2

Find the conjugate of a complex number; use conjugates to find moduli and quotients of complex numbers.

Unpacked Content

Knowledge

Students know:
  • The definition of the conjugate of a complex number.
  • A complex number divided by itself equals 1.
  • The product of a complex number and its conjugate is a real number (the square of the modulus).

Skills

Students are able to:
  • Find the conjugate of a complex number.
  • Find the modulus of a complex number
  • Find the product of two complex numbers.
  • Find (simplify) the quotient of complex numbers.

Understanding

Students understand that:
  • The conjugate of a complex number differs by the sign of its imaginary part and has the same modulus.
  • The modulus of a complex number corresponds to the magnitude of a vector and, therefore, is useful in the geometric representation of complex numbers.
  • Mathematical convention is that radical expressions are not left in denominators to facilitate numerical approximations. therefore, since the i is equal to the square root of -1, conventional form says that i does not appear in the denominator of a fraction.
  • Different forms of a complex number quotient (indicated quotient, single complex number) may be more useful for various purposes.

Vocabulary

  • Conjugate
  • Complex number
  • Modulus/Moduli
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