Bonsoir !
1)
a) AD = AF + FD = (x + 3) + (x - 2) = 2x + 1
b) aire de ABCD = (2x + 1)²
c) aire ABEF = (2x + 1)(x + 3)
d) aire ECDF = (x - 2)(2x + 1)
2)
a) aire ABEF = (2x + 1)(x + 3) = 2x² + 6x + x + 3 = 2x² + 7x + 3
aire ECDF = (x - 2)(2x + 1) = 2x² + x - 4x - 2 = 2x² - 3x - 2
b) ABEF + ACDF = (2x + 1)(x + 3) + (x - 2)(2x + 1)
= (2x + 1)[(x + 3) + (x - 2)]
= (2x + 1)(2x + 1)
= (2x + 1)²
= aire ABCD