Giải thích các bước giải:

 `f(1)=2.1^2+3=5->A` sai

`int_1^2f(x)dx=int_1^2(2x^2+3)dx->B` sai

`int_2^3f(x)dx=int_2^3(2x^2+3)dx->C` sai

`int_0^3 1/2f(x)dx=(int_0^1f(x)dx+int_1^3f(x)dx)/2=(int_0^1(2-x^3)dx+int_1^3(2x^2+3)dx)/2`

$=1/2(2x-1/4 .x^4)|_{\text{0}}^1 $`+1/2 (2/3x^3+3x)|_1^3=(7/4+70/3)/2=301/24->D` đúng