Question

Which of the following is a conjugate for 7 + iSquare root of 2?

1. − 7 + iSquare root of 2
2. 7 − iSquare root of 2

3. iSquare root of 2 + 7

4. iSquare root of 2 − 7

Answer 1

Our complex number is:
7+i√2

Conjugate complex number is a number that has opposite sign of its imaginary part than its original. In this case imaginary part is +i√2
Conjugate value of +i√2 is -i√2 (just change the sign to opposite one)

Answer is:
7 - i√2

Answer 2

Conjugate of a complex number a + ib = a - ib.
Therefore, conjugate of 7 + isqrt(2) = 7 - isqrt(2)