Question

calcule:
A)(√6-2) (9-√6)=
B)(2√5+8) (√5-1)=
me ajudem por favor..

Answer 1

a)

$(\sqrt{6}-2)(9-\sqrt{6})=9\sqrt{6}-(\sqrt{6})^2-18+2\sqrt{6}=-36-18=\boxed{-54}$

b)

$(2\sqrt{5}+8)(\sqrt{5}-1)=2(\sqrt{5})^2-2\sqrt{5}+8\sqrt{5}-8=10+6\sqrt{5}-8\\\\\boxed{=6\sqrt{5}+2}$

Obs :
- Basta aplicar a distributiva
Ex:
$(x+y)(z+f)=xz+xf+yz+yf$