Can you see a pattern? What are the implications for n being either even or odd for ?
I must show that the following equation: cosx+cos2x+...+cosnx=0 accepts at least one solution in .
1)-We know that f(x)=cosx+cos2x+...+cosnx is continious in .
2)-So i must show that , BUT HOW?
CAN YOU HELP ME PLEASE?
AND THANKS ANYWAY.