given x+1/x=2cosy
find x^n +1/x^n
my logic towards the problem is :
since x+1/x>=2..for x+1/x=2cosy to be valid cosy=1..
this implies x=1
thus x^n+1/x^n==1+1=2..
this is for +ve x..so if x is negative answer is -2..
therefore final ans is:
2*sgn(x)
but i am said that i am wrong...i dnt know where and how
plz help
given x+1/x=2cosy
find x^n +1/x^n
my logic towards the problem is :
since x+1/x>=2..for x+1/x=2cosy to be valid cosy=1..
this implies x=1
thus x^n+1/x^n==1+1=2..
this is for +ve x..so if x is negative answer is -2..
therefore final ans is:
2*sgn(x)
but i am said that i am wrong...i dnt know where and how
plz help