SOLUTION
Write out the polynomial
To add the polynomials, we need to add them according to power of address.
Expand, the paranthesis with sign.
[tex]-5x^4+2x^3+8x+2x^4+4x^3+3[/tex]
Collect the terms according to the degrees, we have
[tex]-5x^4+2x^4+2x^3+4x^3+8x+3[/tex]
Adding the terms, we have
[tex]-3x^4+6x^3+8x+3[/tex]
Hence
-3x^4 +6x^3 + 8x + 3
