6 + 42i
Expanding the expression, by using FOIL acronym
(-4+2i)(3-9i)
-12+36i+6i-18i²
-12 +42i -18i² Remember i²= -1
-12 + 42i -18(-1)
-12 + 42i +18
2) Now we have that complex number in the form a +bi
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