2021-01-03 04:14:10 +0100 commented answer Simplify expression with root Great! Thanks a lot! 2021-01-03 04:13:48 +0100 commented answer Integrate() Error Great! Thanks a lot! 2020-12-25 01:02:18 +0100 received badge ● Student (source) 2020-12-25 00:59:40 +0100 asked a question Integrate() Error For: SageMath version 9.0, Release Date: 2020-01-01 When integrating this: t = var('t'); f(t) = (sin(2*t)*sin(t))/(cos(t)+3) a_2 = integrate(f, t, 0, pi)*2/(2*pi) a_2  Output: -17  I get -17 ?! If I just replace sin(2t) with its identity 2sin(t)*cos(t), and integrate again: t = var('t'); f(t) = (2*sin(t)*cos(t)*sin(t))/(cos(t)+3) a_2 = integrate(f, t, 0, pi)*2/(2*pi) a_2  Output:  -(470832*sqrt(2) - 665857)/(13860*sqrt(2) - 19601)  This last value is the correct one. Simplifying this expression (which I don't know how to do in Sage), you have: (12*sqrt(2)-17)  It seems like the first result, wrongly reporting -17, somehow is missing the 12*sqrt(2) part of it. 2020-12-25 00:59:40 +0100 asked a question Simplify expression with root The result of some integral, computed using integrate(), is: 2*(2378*sqrt(2) - 3363)/(408*sqrt(2) - 577)  However, when I do the integral "by hand" I get 2*(3-2*sqrt(2))  Numerically both results are the same, but the first result is a lot more complicated. Multiplying separately the numerator and denominator of the first expression by (408*sqrt(2) + 577) brings the correct result. What can I do to simplify the first expression and get something really simple, as the second one? Thanks in advance!