Hello,
Step-by-step explanation:
f(x) = 2x² - 7x + 3
f(x+h) = 2(x+h)² - 7(x+h) + 3 = 2x² + 4xh + 2h² - 7x - 7h + 3
f(x+h) - f(x) = 2x² + 4xh + 2h² - 7x - 7h + 3 - 2x² + 7x - 3
= 4xh + 2h² - 7h
(f(x+h) - f(x))/h = (4xh + 2h² - 7h)/h = 4x + 2h - 7
f'(x) = 4x - 7
because when h → 0 ; 2h → 0
