Answer
$x^{34}+17x^{32}+136x^{30}$
Work Step by Step
Calculate the first three terms of $(x^2+1)^{17}$ by using Binomial Theorem or Binomial expansion.
This implies
$(x^2+1)^{17}=\displaystyle \binom{17}{0}(x^2)^{17}1^0+\displaystyle \binom{17}{1}(x^2)^{16}1^1+\displaystyle \binom{17}{2}(x^2)^{15}1^2$
or, $=x^{34}+17(x^{32})(1)+136x^{30}(1)$
or, $=x^{34}+17x^{32}+136x^{30}$