bonjour
f (x) = - 105 x² + 1 000 x + 500
f ( x) = - 105 ( x - 10 ) ( x + 10 /21)
f ( x) = (- 105 x + 1050) ( x + 10/21 )
f ( x) = - 105 x² - 1050 x / 21 + 1 050 x + 10 500 /21
f ( x) = - 105 x² - 1 050 x /21 + 22 050 x /21 + 10 500 /21
f ( x) = - 105 x² + 21 000 x / 21 + 10 500 /21
f ( x) = - 105 x² + 1 000 x + 500
