bonjour
ton équation est fausse au départ
0.6 q ( q + 5 ) / q + 5 = ( 40 - 2 q ) / ( q + 5 )
0.6 q² + 3 q = 40 - 2 q
0.6 q² + 3 q + 2 q = 40
0.6 q² + 5 q - 40 = 0
Δ = 5² - 4 ( 0.6 x - 40 ) = 25+ 96 = 121
x 1 = ( - 5 - 11) / 1.2 = - 16 /1.2 = - 160 /12 = - 4
x 2 = ( - 5 + 11 ) / 1.2 = 6 / 1.2 = 60 /12 = 5
