Let a + bi and c + di be complex numbers. 1. Add/Subtract the Real parts. 2. Add/Subtract the Imaginary parts . <ul><li>(3 + 4i) + (2 - i) = (3 + 2) + (4i - i) = (5 + 3i) </li></ul><ul><li>(7 + i) - (3 - i) = (7 - 3) + i(1 - (-1)) = 4 + 2i </li></ul>
Let a + bi and c + di be complex numbers. 1. Multiply the binomials. 2. Convert i 2 to -1 and add the like terms. (3 + 2i)(4 + 5i) = (3 × 4) + (3 × (5i)) + ((2i) × 4) + ((2i) × (5i)) = 12 + 15i + 8i + 10i² = 12 + 23i -10 (Remenber that 10i² = 10(-1) = -10) = 2 + 23i Therefore, (3 + 2i)(4 + 5i) = 2+23i
<ul><li>A complex number z is a number of the form z = x + yi . Its conjugate is a number of the form = x - yi . The complex number and its conjugate have the same real part. Re( z ) = Re( ). The sign of the imaginary part of the conjugate complex number is reversed. Im( z ) = - Im( ). </li></ul><ul><li>The conjugate numbers have the same modulus and opposite arguments. | z | = | |, arg( z ) = - arg( ). Any complex number multiplied by its complex conjugate is a real number, equal to the square of the modulus of the complex numbers z . z = ( x + yi )( x - yi ) = x 2+ y 2 = | z |2 </li></ul>
Division Of Complex Numbers Let a + bi and c + di be complex numbers. Multiply the numerator and denominator of the fraction by the Complex Conjugate of the Denominator . Then to perform the operation 2+6i x 4-i = (2+6i) (4-i) = 14+22i = 14 + 22 i 4+i 4-i (4+i) (4-i) 17 17 17
Real Axis Imaginary Axis y x The angle formed from the real axis and a line from the origin to ( x , y ) is called the argument of z , with requirement that 0 < 2 . modified for quadrant and so that it is between 0 and 2 Let a complex number be Z such that : z Modulus and Argument of Complex Numbers The magnitude or modulus of z denoted by z is the distance from the origin to the point ( x , y ).
The Principal Argument is between - and Real Axis Imaginary Axis y x z = r 1 The unique value of θ such that – π < θ < π is called principle value of the argument. but in Quad II
The magnitude or modulus of z is the same as r. We can take complex numbers given as and convert them to polar form : Real Axis Imaginary Axis y x z = r Plot the complex number: Find the polar form of this number. 1 factor r out but in Quad II