my teacher changed the bounds of this problem #1 but not on problem #2 when do you know to change the bounds? please help. my test is in 2 hours.

PROBLEM 1

integral (upper bound 4, lower bound 1) dx/ ( (sqrtx) * (2sqrtx +3))

he set u= 2sqrtx +3

consequently du= dx/sqrtx

he then substituted to make the new upper bound 7 and the new lower bound 5.

i understand why he did that, but why didnt he change the bounds in this problem:

integral (upper bound e; lower bound 1) ln(x)dx

he set u=lnx du=dx/x

dv=dx v=x

why did he keep the same (upper bound e; lower bound 1) while he integrated by parts???