Chain Reaction @ 02

Algebra Level 2

If N ( x 2 2008 1 1 ) = ( x + 1 ) ( x 2 + 1 ) ( x 4 + 1 ) . . . . . ( x 2 2007 + 1 ) 1 N(x^{2^{2008}-1}-1)=(x+1)(x^{2}+1)(x^{4}+1). . . . .(x^{2^{2007}}+1)-1 , then number of solutions of |N|=1 is/are :

4 2 0 3 1

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Saurav Pal
Apr 26, 2015

We are given that N ( x 2 2008 1 1 ) = ( x + 1 ) ( x 2 + 1 ) ( x 4 + 1 ) . . . . . ( x 2 2007 + 1 ) 1 N(x^{2^{2008}-1}-1)=(x+1)(x^{2}+1)(x^{4}+1). . . . .(x^{2^{2007}}+1)-1 . So, by multiplying by x 1 x-1 on both sides we get, N ( x 1 ) ( x 2 2008 1 1 ) = ( x 2 2008 1 ) ( x 1 ) N(x-1)(x^{2^{2008}-1}-1)=(x^{2^{2008}}-1)-(x-1) N ( x 1 ) ( x 2 2008 1 1 ) = ( x 2 2008 x ) N(x-1)(x^{2^{2008}-1}-1)=(x^{2^{2008}}-x) N ( x 1 ) ( x 2 2008 x ) ( x ) = ( x 2 2008 x ) N(x-1)\frac{(x^{2^{2008}}-x)}{(x)}=(x^{2^{2008}}-x) N = x x 1 N=\large{\boxed{\frac{x}{x-1}}} . Now we are asked to find the number of solutions of the equation, x x 1 = 1 \left| \frac { x }{ x-1 } \right| =1 CASE @ 1 x x 1 = 1 \frac { x }{ x-1 } =1 \Rightarrow No Solution.

CASE @ 2 x x 1 = 1 \frac{x}{x-1}=-1 \Rightarrow x = 1 2 \boxed{x=\frac{1}{2}} .

\therefore no. of solutions of |N|=1 is 1 \boxed{\boxed{1}}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...