Final answer:
When dealing with definite integrals and substituting U back into terms of x, you should add a constant to the result.
Step-by-step explanation:
When dealing with definite integrals and substituting U back into terms of x, you should add a constant to the result. This is because when you substitute U back into terms of x, you are essentially finding a new function in terms of x. Adding a constant to the result allows for the inclusion of all possible solutions.