Learning a new subject and just need some help Thanks

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