The Attempt at a Solution
I set 3x=4secy, 3dx=4secytany and (9x2-16)1/2=2tany.
I then plugged that all into my integral and ended up with2tany*4secytany/(4/3secy)4 dy...
(81/32) tan2y/sec3y dy....
I solved for this by switching tan and sec to cos and sin, so (81/32) cos3y*sin2y/cos2y.... and integrated that to get (81/32)sin3/3+c.... when it's all worked out I had 32/x3
I can't figure out where I went wrong but I'm certain that I haven't got the right answer. Thanks!