+23254 If f(x) = x² -2x + 2
then f(x + h) = (x + h)² - 2(x + h) + 2
= x² + 2xh + h² - 2x - 2h + 2
[f(x + h) - f(x)] / h = [ ( x² + 2xh + h² - 2x - 2h + 2 ) - ( x² -2x + 2 ) ] / h
= [ x² + 2xh + h² - 2x - 2h + 2 - x² + 2x - 2 ) ] / h
= [ 2xh + h² - 2h ] / h
= 2x - 2 + h
