bonjour,
soit x la longueur, y la largeur
2x+2y = 62
on simplifie par 2 : x+y = 31
surface = xy
on augmente 2 à x, on diminue y de 1, surface inchangée
(x+2)(y-1) = xy
xy-x+2y-2 =xy
xy-x+2y-2-xy = 0
-x+2y = 2
x+y = 31
-x+2y = 2
3y = 33
y = 11
x+y = 31
x+11 =31
x = 31-11 = 20
longueur = 20
largeur = 11
A = 20*11 = 220
on augmente L de 2 = 22
on diminue l de 1 = 10
22*10 = 220