You can use this to simplify complex fractions. Multiply the numerator and denominator by the complex conjugate of the denominator to make the denominator real. 3 - 7i 3 - 4i +i Two convenient functions to know about pick out the real and imaginary parts of a complex number. Re(a + ib) = a (the real part (coordinate) of the complex number), and Im(a + ib) = b (the imaginary part (coordinate) of the complex number. Re and Im are linear functions -- now that you know about linear behavior you may start noticing it often.