a) (a+2)(a-2)=
b) (x+1)(x-1)=
c) (7-y)(7+y)=


Răspuns :

Folosim formula diferenței de pătrate:
(a-b)(a+b)=a²-b²

a) (a+2)(a-2)=a²-2²=a²-4

b) (x+1)(x-1)=x²-1²=x²-1

c) (7-y)(7+y)=7²-y²=49-y²
a) (a+2)(a-2)=a²-2²=a²-4
b) (x+1)(x-1)=x
²-1
c) (7-y)(7+y)=7²-y²=49-y²