Answer
$3a^{3}+4a^{3}b+17a^{2}b-17ab^{2}$
Work Step by Step
$17a^{2}b-16ab^{2}+3a^{3}+4ba^{3}-b^{2}a$
Rewrite the expression by putting all the $a$'s right after the coefficient in every term:
$17a^{2}b-16ab^{2}+3a^{3}+4a^{3}b-ab^{2}=...$
Simplify the expression by combining like terms:
$...=3a^{3}+4a^{3}b+17a^{2}b-(16+1)ab^{2}=...$
$...=3a^{3}+4a^{3}b+17a^{2}b-17ab^{2}$