Which of the following is the conjugate of 6 + 7i?
Conjugate of a real number has no physical significance.
Answer: Conjugate of 6 + 7i is 6 - 7i.
Conjugate is defined for complex numbers, mostly.
A conjugate of a complex number means the complimentary of a complex number, such that when the complex and its conjugate are added, it results in the twice of the real part, and the imaginary part gets canceled.
In other words, a conjugate means just changing the sign of the imaginary part of the complex number.