Question

calculați
(a+2)(a-2)
( x+1(x-1)
(7-y)(7+y)

Answer 1

(a+2)(a-2)= a^{2} -2^{2}= a^{2}- 4
(x+1)(x-1)= $x^{2}$ -1^{2}= $x^{2}$ - 1
(7-y)(7+y)= 7^{2} - y^{2}= 49- y^{2}