Question

Multiply: 

i) \( (4-i)(3-5 i) \) 

ii) \( (4+ i )(3- i ) \)

Answer 1

(i) \((4 - i) (3 - 5i)\)

\(= 12 + 5i^2 -3i - 20i\)

\(= 7 - 23i\)       (\(\because i^2 = -1\))

(ii) \((4 + i)(3 - i)\)

\(= 12 - i^2 + 3i - 4i\)

\(= 13 - i\)