Bonjour !
On utilise la formule (u/v)' = (u'v-uv')/v²
-> f'(x) = (4x(-4x+2)-(2x^2+1)(-4))/(-4x+2)^2
= (-16x^2 + 8x + 8x^2 + 4)/(-4x+2)^2
= (-8x^2+8x+4)/(-4x+2)^2
-> g'(x) = (5(8-x)-(5x+2)(-1))/(8-x)^2
= (40-5x+5x+2)/(8-x)^2
= 42/(8-x)^2
-> h'(x) = 5 - 0 + ((6x+4)5x-(3x^2+4x)5)/(5x)^2
= 5 + (30x^2 + 20x - 15x^2 - 20x)/(25x^2)
= 5+(15x^2)/(25x^2)
= 5 + 15/25
= 5 + 3/5
= 28/5
N'hésite pas si tu as des questions :)
