f[x_]:=x^3+2*x; a=-1; b=3;
FilledPlot[f[x],{x,a,b},AspectRatio->1]
![[Graphics:../Images/quiz6-answers_gr_1.gif]](../Images/quiz6-answers_gr_1.gif)
INT=Integrate[f[x],{x,a,b}]
n=2;
LEFT[n]=LeftEndpointRule[f,{a,b,n}]
RIGHT[n]=RightEndpointRule[f,{a,b,n}]
TRAP[n]=TrapezoidRule[f,{a,b,n}]
MID[n]=MidpointRule[f,{a,b,n}]
SIMP[n]=SimpsonRule[f,{a,b,n}]