Let’s go
1) A=(x+7)^2-(x+7)(2-3x)
A= x^2 + 7x + 7x + 49 - 2x + 3x^2 - 14 + 21x
A = 4x^2 + 33x + 35
2 ) A = x ( 4x^2 + 33 + 35/x )
3 ) a) on a A = (0+7)^2-(0+7)(2-3x0)
Donc A = 49 - 14
A = 35
b) A= (-7+7)^2-(-7+7)(2-3x-7)
A = 0
c) A = (-5/4+7)^2-(-5/4+7)(2-3x-5/4)
A = 529/16 - 529/16
A = 0
d) A= (3+7)^2-(3+7)(2-3x3)
A = 100 - ( - 70 )
A = 170
Et voilà ^^