Question

CMR : a² - (a-1) . (a+1) = 1

Answer 1

tìmn ez

a)n 1la uoccua 3

b)uoc cua n 7

Answer 2

Ta có: a²-(a-1)(a+1)

= a²-(a²-a+a-1)

= a²-a²+a-a+1

=1

Vậy a²-(a-1)(a+1)=1 (đpcm)