Python TypeError:^不支持的操作数类型(s):“浮动”和“int”

I wrote a simple program which approximates the evaluation of a definite integral using numerical integration. However, I am stumped when it comes to why I am getting the error in the title. Keep in mind that I haven't touched python in one and a half years so it might be something incredibly obvious that I'm missing, however I'd still be grateful if you could help me :) Here is the code:I wrote a simple program which approximates the