bonjour
f (x) = 4.2 x
f ( - 1 ) = - 1 * 4.2 = - 4.2
f ( 0 ) = 0
f ( 2) = 2 * 4.2 = 8.4
f ( 10) = 10 * 4.2 = 42
f ( 100 ) = 100 * 4.2 = 420
f ( 1 000) = 1 000 * 4.2 = 4 200
4.2 x = 7
x = env 1.67
4.2 x = 0.6
x = 0.14 env
4.2 x = 81
x = 19.28 env
4.2 x = 10.5
x = 2.5
bon WE