The conjugate of the complex number a + bi is the complex number a - bi . In other terms, it is the original complex number along the sign on the imaginary part changed. Here are some instance of complex numbers and their conjugates.
complex number conjugate
3+ (½) i 3 - (½) i
12 - 5i 12+ 5i
1 - i 1+i
Note that the conjugate of a real number is only itself with no changes.