bonsoir,
1)EC = DC - ED
EC = (2x - 3) - (x + 1)
Aire ABCD = (2x -3)²
Aire AFED = (2x - 3) (x +1)
Aire BCEF = aire ABCD - aire AFED
donc A = (2x - 3 )² - (2x -3) (x +1)
2) A = 4x² - 6x +9 - ( 2x² + 2x - 3x -3)
A = 4x² -6x +9 - 2x² -2x +3x +3)
3)
A = 2x² - 5x +12
4) Aire BCEF pour x = 5
A = 2x² -5x +11
A = 2(5)² - 5x5 + 12
A = 50 - 25 + 12
A = 37
