Răspuns:
Explicație pas cu pas:
x = 10√2 - 9√2 = √2
y = (2/√5 + 2/√20 - 7/√125) : 8/5√5
= (2/√5 + 2/2√5 - 7/5√5) *5√5/8
= (2/√5 + 1/√5 - 7/5√5)*5√5/8
= (3/√5 - 7/5√5)*5√5/8
= (15/5√5 - 7/5√5)*5√5/8
= 8/5√5*5√5/8 = 1
y - x^2 = 1 - (√2)^2 = 1 - 2 = -1
(-1)^2020 = 1
