Please show clear steps including changing variable.
Hints: [(secx)^4 - (cscx)^4]^2 dx = (secx)^8 - 2 (secx)^4 (secx)^2/(tanx)^2 + (secx)^4/(tanx)^4
更新1:
Ans: (tanx)^7 / 7 + 3 (tanx)^5 / 5 + (tanx)^3 / 3 - 3 tanx - (cotx)^3 / 3 + cotx + C
