Why did farming and trade revive in the high middle ages?

To be able to survive

Because they needed crops to survive and the needed wet lands

Perhaps saving more money for their retirement and getting better life insurance for jackie. and trying to spend less money on unnecessary expenses always . 

To solve this integral, what you can do is split it up as follows: (1) ∫40(x2−4)dx=∫40(x2)dx−∫40(4)dx. to integrate  4  as an  indefinite integral, a good rule of thumb is  by  an equation below  for  polynomials; . (2) ∫xa=xa+1a+1+c , where a is any number. c denotes some constant that is crucial when doing