If you're multiplying these terms with imaginary parts, do it just like you would any binomial multiplication. (4x+3i)(7x+4i). FOIL-ing that out we get, before simplification, [tex]28 x^{2} +16ix+10ix+12 i^{2} [/tex]. There are 2 things to simplify here: Combining like terms and then dealing with the squared i. [tex] i^{2} [/tex] is equal to -1, so 12(-1) = -12. Then we will combine the ix terms and in the end we will have [tex]28 x^{2} +26ix-12[/tex]
