1) x
x + 1
( x + 1)²
( x +1)² - x² = ( x + 1 - x) ( x + 1 + x) = 2 x + 1
f(x) = 2 x + 1 de forme ax + b donc fonction affine
n² - ( n + 1)² = 2 009
(n + n + 1)( n - n - 1) = 2009
2 n ( - 1) = 2009
- 2 n = 2009
n = - 1004.5
2 n ( -1) = 2010
- 2 n = 2010
n = - 100 5
