Does anybody know much about how this works? I can't understand why it doesn't give me an answer for definite integrals sometimes... e.g. in Matlab R2011a: syms x a; int(x/sqrt(x^2+a^2)) gives the answer (a^2 + x^2)^(1/2) as expected. But int(x/sqrt(x^2+a^2),0,10) gives - Warning: Explicit integral could not be found. This doesn't really make any sense as the answer should be (a^2 + 10^2)^(1/2) - a. Is there some way to understand this strange behavior?