a).(7-x)(7+x) b).(1-y)(1+y) c).(1-3x)(1+3x) d)(5b+2)(5b-2) Aider moi svp !!!

identite remarquable pour l ensemble soit (a-b)(a+b) = a²-b²
donc
A).(7-x)(7+x)a = 7²-x² = 49 -x²

b).(1-y)(1+y) = 1 -y²

c).(1-3x)(1+3x) = 1 -9x²

d)(5b+2)(5b-2) = 25b² -4

c'est l'identité remarquable a²-b² = (a+b)(a-b)
a)
(7-x)(7+x) = 7²+7x-7x-x² = 49-x²

b)
(1-y)(1+y) = 1+y-y-y² = 1-y²

c)
(1-3x)(1+3x) = 1+3x-3x-9x² = 1-9x²

d)
(5b+2)(5b-2) = 25b²-10b+10b-4 = 25b²-4