Bonjour
Aire ABCD = 80
5)
Aire AMIJ = x²
Aire CKIH = (8-x)(10-x)
6)
d) 0 < x < 8
S(x) = Aire AMIJ + Aire CKIH = x²+(8-x)(10-x)
S(x) = 2x²-18x+80
e)
S(x) = 1/2 Aire ABCD
2x²-18x+80 = 40
2x²-18x+40 = 0
2(x-4)(x-5) = 0
deux solutions x' = 4 ou x" = 5
car (x-4)(x-5) = x² - 9x + 20
