This is what i need help with
Next time posting code, post it as text. You make it hard to copy and paste code.
In the function f(), you pass in one variable, called x. In the function you use h, a and b. Those will not be available, they are not passed in nor a local variable. You are saying that your function only depends on one parameter, so make it so.
The same for the function trapezium. Suddenly you use variables xb and h which are not passed in, nor a local variable.
The idea of the algorithm is that you calculate the function for points that are h units apart, so I think you mean the first line of your trapezium function to read
h = (xn - x0) / n. Now h is a local variable and the “x-distance” between points.
The number of points in range(1, n - 1) is n - 1 and not n.
The remainder looks OK.