How do you multiply #(7+3i)(-7+5i)(-8-4i)#?
1 Answer
Mar 9, 2018
Explanation:
#"multiply any pair of factors using FOIL and then"#
#"multiply the result by the third remaining factor"#
#color(orange)"Reminder"color(white)(x)i^2=(sqrt(-1))^2=-1#
#rArr(7+3i)(-7+5i)#
#=-49+14i+15i^2=14i-64#
#rArr(14i-64)(-8-4i)#
#=-112i-56i^2+512+256i#
#=568+144i#
