how to solve with extra addend 1 in the integral?
To deal with the 1 in this integral, you can break up the original integral as follows:
∫[1+√(9-x^2)]dx = ∫1dx + ∫√(9-x^2)dx
*Note: I have indicated these as indefinite integrals because there is no way to nicely format definite integrals on here.
From there, you take the definite integrals each separately as you normally would, and add them together to find the answer.
Hope this helps! Let me know if you have any further questions.