bonsoir
f (x) = - 4 x + 5
f ( 4) = - 4 *4 + 5 = - 16 + 5 = - 11
f ( - 9 ) - 4 * - 9 + 5 = 36 + 5 = 41
f ( 3/7) = - 4 * 3/7 + 5 = - 12 /7 + 35/7 = 23/7
- 4 x + 5 = 17
- 4 x = 17 - 5
- 4 x = 12
x = - 3
- 4 x + 5 = - 4
- 4 x = - 4 - 5
- 4 x = - 9
x = 9 /4