cine ma ajuta dau coroană urgent ex8a si dex9c si f

Răspuns:
8)
a)(√2-1)(√2+1)=2-1=1
9)
c)(9a-b²)(b²+9a)=(9a-b²)(9a+b²)=81a²-b⁴
f)(a³-b²)(a³+b²)=(a³)²-(b²)²=a⁶-b⁴