Again, I'd try graphing this thing and get your point this way. Go to Wolframalpha dot com Put
y = 2x^4 + 3x^3 - 16x - 24 into the input line.
According to wolframalpha there are 2 real roots and 2 imaginary ones.
there are places on the internet that will solve quartics for you and likely those solutions will show all 4 roots. You were right to be a little suspicious, but the question is a bit unreasonable.
Note to Moderator. Wolframalpha dot com is just a tool. the work is my own.
