a) 6x
2 + 5x + 1 = 0, cu a = 6, b = 5, c = 1 si ∆ = 52 − 4 · 6 · 1 = 1;
b) 9x
2 − 12x + 4 = 0, cu a = 9, b = −12, c = 4 si ∆ = (−12)2 − 4 · 9 · 4 = 0;
c) x
2 − x − 2 = 0, cu a = 1, b = −1, c = −2 si ∆ = (−1)2 − 4 · 1 · (−2) = 9;
d) −
1
2
x
2 +
√
3x − 4 = 0, cu a = −
1
2
, b =
√
3, c = −4 si ∆ = (√
3)2 − 4
−
1
2
(−4) = −5.
