A={xεR:X^11+2X^5<2} let a=supA By choosing a suitable sequence of elements of belonging to A and which tends to a as n->inf, or otherwise, show that a^11+2a^5=<2.Choose another sequence this time of all real numbers not belonging to A to show that a^11+2a^5>=2 and hence show that a^11+2a^5=2,so...
im trying to solve this excersice but i couldn't find any similar questions like this one
find for which real x the series SIGMA x^n/1+x^2n converges and for which it diverges