Question

What is 4x + 3i * 7x +4i

Answer 1

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,
`28 x^(2) +16ix+10ix+12 i^(2)`. There are 2 things to simplify here: Combining like terms and then dealing with the squared i.
`i^(2)` is equal to -1, so 12(-1) = -12. Then we will combine the ix terms and in the end we will have
`28 x^(2) +26ix-12`