1.

Write down the conjugate of each of the following : `(i)" "(-5+sqrt(-1))" "(ii)" "(-6-sqrt(-3))" "(iii)" "i^(3)" "(iv)" "(4+5i)^(2)`

Answer» We know that the conjugate of z = (a + ib) is given as `bar(z) = (a - ib)`.
(i) Let `z = -5+sqrt(-1)=(-5+i)`. Then,
`bar(z) = bar((-5+i))=(-5-i)`.
(ii) Let `z = -6- sqrt(-3) = -6 - i sqrt(3)`. Then,
`bar(z) = bar((-6-i sqrt(3))) = (-6 + i sqrt(3))`.
(iii) Let `z = i^(3) = -i = 0 - i`. Then,
`bar(z)=bar((0-i))=(0+i)=i`.
(iv) Let `z = (4+5i)^(2)=(4)^(2) + (5i)^(2)+2 xx 4 xx 5i`
`=(16 - 25 + 40i)=(-9+40i)`.
`bar(z)=bar((-9+40i))=(-9-40i)`.


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