Răspuns:
-5/12=-0,416
Explicație pas cu pas:
a = {[1 - 1,(6)]² × 1,5 - 1,8(3)} : 2,8= {[1 - 1 6/9]² × 1,5 - 1 (83-8)/90} : 2,8.=
[(1-5/3)²×1,5-1 75/90]:2,8=[(-2/3)²×1,5-1 5/6]:2,8=
(4/9×1,5-11/6):2,8=[(4×15)/90-11/6]:28/10=
(4/6-11/6)×10/28=-7/6×5/14=-(7×5)/(7×12)=-5/12=-0,416
