Answer
$-3$
Work Step by Step
$(x^{2}+1)^{5}(x+3)^{4}+(x^{2}+1)^{6}(x+3)^{3}=0$
$(x^{2}+1)^{5}(x+3)^{3}((x+3)+(x^{2}+1))=0$
$(x^{2}+1)^{5}(x+3)^{3}(x^{2}+x+4)=0$
$(x^{2}+1)^{5}=0, x^{2}+1=0, undifined, x$ $is $
$imaginary$ $ number$
$(x+3)^{3}=0, x+3=0, x=-3$
$x^{2}+x+4=0, undifined, x$ $is$ $imaginary $ $number$
