Răspuns:
25x^2 - 20x + 4 = 0
delta = (-20)^2 - 4 × 25 × 4
delta = 400 - 400
delta = 0
=>x1 = x2 = 20/50 = 2/5
a) 2/5 + 2/5 - 4/25 = 16/25
b) 5/2 + 5/2 = 10/2 = 5
c) 4/25 + 4/25 = 8/25
d) 25/4 + 25/4 = 50/4 = 25/2