Bonjour !
f(x) = mx + n
Donc f(4)-f(0) = (m*4+n) - (m*0+n) = 4m+n-0-n = 4m
Or on sait que f(4)-f(0) = 5
Donc 4m = 5
<=> m = 5/4 = 1.25
1) f(45)-f(41) = 45m+n-41m-n = 45m-41m = 4m = 4*1.25 = 5
Bon en fait on peut arrêter de prendre en compte l'ordonnée à l'origine.(n)
2) f(22)-f(20) = 22m-20m= 2m = 2*1.25 = 2.5
3) f(101)-f(100) = 101m-100m = 1*m = 1*1.25 = 1.25
4) f(-8) - f(0) = -8m-0m = -8*m = -8*1.25 = -10
Bon je pense que tu as compris le principe.
5) f(-26)-f(-42) = -26m-(-42)m = -26m+42m = 16m = 16*1.25 = 20
6) f(-116) - f(100) = -116m-100m = -216m = -216*1,25 = -270
Voilà.
