Bài giải:

Ta có: g(x) =  $5-4x-3{{x}^{2}}-2{{x}^{3}}+{{x}^{4}}+{{x}^{5}}$

g(x) = ${{x}^{5}}+{{x}^{4}}-2{{x}^{3}}-3{{x}^{2}}-4x+5$

Suy ra: h(x) = f(x) + g(x) = (${{x}^{5}}+4{{x}^{4}}+3{{x}^{3}}+2{{x}^{2}}+x+1$) + (${{x}^{5}}+{{x}^{4}}-2{{x}^{3}}-3{{x}^{2}}-4x+5$)

= $({{x}^{5}}+{{x}^{5}})+(4{{x}^{4}}+{{x}^{4}})+(3{{x}^{3}}-2{{x}^{3}})+(2{{x}^{2}}-3{{x}^{2}})+(x-4x)+(1+5)$

= $2{{x}^{5}}+5{{x}^{4}}+{{x}^{3}}-{{x}^{2}}-3x+6$

Đáp án đúng là: C