Math equations like challenging algebra (simplify or solve for x) equations, trigonometry or trig identity equations, complex number equations, and tons of tricky integration bee problems (elementary integrals).
Currently I have AOPS textbooks (the basics and the beyond), mainly for their cool equations, and Spivak's calculus textbook for the miscellaneous integrals (which seemed like integration bee problems to me.
Do you guys know any textbooks with tons of challenging fun math equations?
Thank you.