An easy way to multiply binomials is the FOIL(first, outer, inner, last) method. Multiply the first terms of each binomial, -3i×3i=-9i^2. Then do the outer terms, -3i×4=-12i. Then do the inner terms 4×3i=12i. Then do the last terms, 4×4=16. Lastly combine like terms, the -12i and 12 cancel out, and you're left with -9i^2+16. i^2=1, so then you get -9(-1)+16. -9×-1=9. 9+16=25
