How do you multiply #(5-3i)(-8+5i)#?

1 Answer
shr
Oct 31, 2016

#(5-3i)(-8+5i)=-25+49i#

Explanation:

We must use the distributive property to expand these two binomials:

#(5-3i)(-8+5i)#
#=-40+25i+24i-15i^2#

Note that #i^2 = sqrt-1 * sqrt-1 = -1#

#=-40+49i-15(-1)#
#=-40+15+49i#
#=-25+49i#

Remember the answer must be in the form #a + b i# where a is a constant and b is the coefficient on the #i# term.

#:.(5-3i)(-8+5i)=-25+49i#

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