Question

a) ( 8 - i) ( - 1 + i)
b) (3 - i) ( 7 - i )
c) ( - 10 ) ( - 3 i
d) (4 - 2 i ) ( - 1 + 2 i )

Answer 1

$(8-i)(-1+i) = \\-8+8i+i-i^{2} =\\ -8+9i-(-1) =\\ -7+9i$

$(3-i)(7-i) = \\21 - 3i - 7i + i^{2} = \\21 - 10i -1 = \\20 - 10i$

$-10*(-3i) = 30i$


$(4-2i)(-1+2i) = \\-4 + 8i +2i -4i^{2} = \\-4 +10i -4*(-1) = \\10i$