[tex] x^{4} + 3 x^{3} - 2x^{3} - 5 x^{2} - x + x^{2} + x + 1 + 7 x^{4} [/tex]
Collect the terms. Meaning, collect all exponents in to one whole exponent (e.g. combine the x^4 and 7x^4).
[tex]8x^{4} + x^{3} - 4 x^{2} + 1[/tex]
Therefore your answer is [B].
