Tolong bantuannya sama caranya plissss

Mapel : Matematika
Bab : Akar dan Pangkat

(√2 - 2) (4 + √2)
= √2 (4 + √2) - 2 (4 + √2)
= 4√2 + √4 - 8 - 2√2
= 4√2 + 2 - 8 - 2√2
= 2√2 - 6
= -6 + 2√2

a = -6 ,  b = 2

Maka,
Nilai a - b
= -6 - 2
= -8