func = @(x) 1/(6*x*x*x)
mx= 9;
mi = 1;
n = 20;
h=(mx-mi)/n;
result = 0;
for i=1:n
  x0=mi+(i-1)*h;
  x1=mi+(i*h);
  result=result+(func(x0)+ func(x1))*h/2;
end
disp(['estimitted integral:', num2str(result)]);