How do you multiply (1+4i)(3+6i)?

1 Answer
Jade ยท Daniel L.
Sep 25, 2016

FOIL

Explanation:

Multiply the First terms in each set of parenthesis. 1 xx 3 = 3
Multiply the Outer terms of each set of parenthesis. 1 xx 6i = 6i
Multiply the Inner terms of each set of parenthesis. 4i xx 3 = 12i
Multiply the Last terms in each set of parenthesis.
4i xx 6i = 24i^2=-24
First, Outer, Inner, Last - FOIL

So, the answer would be 3 + 6i +12i - 24
Add like terms: 6i + 12i = 18i , 3-24=-21

(1 + 4i) (3 + 6i)= -21 + 18i

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