I am assuming that you want to know the reason behind the solution being an analytic expression instead of a numeric answer. According to the documentation on symbolic integral function “int()”, it returns a symbolic expression as output.
To get a numeric answer, you may use the “vpa” function in MATLAB. This function evaluates the symbolic input to 32 significant digits (by default). In addition, it also provides the provision to limit the number of significant digits by taking a second input argument. In this case, the expression evaluates to
Please refer to the following documentation link on “vpa” for any further clarifications.