Section 4.6 Complex Numbers
it is a symbol for a specific number Definition of pure imaginary numbers: i is not a variable it is a symbol for a specific number
Definition of pure imaginary numbers: Any positive real number b, where i is the imaginary unit and bi is called the pure imaginary number.
Simplify each expression.
Simplify each expression. Remember Remember
Definition of Complex Numbers Any number in form a+bi, where a and b are real numbers and i is imaginary unit.
Definition of Equal Complex Numbers Two complex numbers are equal if their real parts are equal and their imaginary parts are equal. If a + bi = c + di, then a = c and b = d
When adding or subtracting complex numbers, combine like terms.
Simplify.
Simplify.
Multiplying complex numbers. To multiply complex numbers, you use the same procedure as multiplying polynomials.
Simplify. F O I L
Simplify. F O I L
To divide complex numbers, multiply the numerator and denominator by the complex conjugate of the complex number in the denominator of the fraction. 7 + 2i 3 – 5i The complex conjugate of 3 – 5i is 3 + 5i.
7 + 2i 3 – 5i (3 + 5i) (3 + 5i) 21 + 35i + 6i + 10i2 9 + 15i – 15i – 25i2 11 + 41i 34 21 + 41i – 10 9 + 25