The techniques used on this page use a special package which must be called by using the following command:
> with(student);

> A:=Int(sin(3*x+5),x);

> changevar(3*x+5=u,A,u);

> value(");

> subs(u=3*x+5,");


> A:=Int(5*x/(1+16*x^4),x);

> changevar(4*x^2=u,A,u);

> value(");

> subs(u=4*x^2,");


> A:=Int(8*(sec(4*x))^2/(5-3*tan(4*x))^7,x);

> changevar(5-3*tan(4*x)=u,A,u);

> value(");

> subs(u=5-3*tan(4*x),");

Alternative way:
> changevar(tan(4*x)=u,A,u);

> B:=";

> changevar(-5+3*u=v,B,v);

> value(");

> subs(v=-5+3*u,");

> subs(u=tan(4*x),");


> A:=Int(5*exp(2*x)/(7+9*exp(2*x)),x=0..3);

> changevar(7+9*exp(2*x)=u,A,u);

> value(");

These integrals are solved without using Maple on this page.