bonjour
f (x) = - 5 x² + 9
f ( 1) = - 5 ( 1 )² + 9 = - 5 + 9 = 4
f ( - 3 ) = - 5 ( - 3 )² + 9 = - 45 + 9 = - 36
f ( 0 ) = 9
f ( 1/3) = - 5 ( 1 /3)² + 9 = - 5 * 1/9 + 9 = - 5/9 + 81/9 = 76 /9
f ( 2.3) = - 5 ( 2.3)² + 9 = - 5 * 5.29 + 9 = - 26.45 + 9 = - 17.45