Question

Simplify the given expression
(1+2i) ∙ (5-3i)

a) 2-15i
b) 3+2i
c) 5-6i
d) 11+7i


Can someone help me solve this?

Answer 1

(1+2i)*(5-3i)
5-3i+10i-15i^2
5+7i-15i^2

Answer 2

But 15i^2 = -15 becuase i^2 = -1

Final answer: 20 + ti

Answer 3

Error...soduko..in multiplication...

(1+2i)(5-3i) = 5 + 10i - 3i - 6i^2
= 5 + 7i + 6
= 11 + 7i

Answer 4

foil method.

Answer 5

ya I forgot about the fact that i^2=-1 cuz I haven't been in a math class for almost half a year

Answer 6

http://www.mathwords.com/f/foil_method.htm