1)
x1 = 
x2 = 
x3 = 
x4 = 
2)
x1,2 = ±
Объяснение:
1) х² = у
у² -10у +1 = 0
D = 100 - 4 = 96
y1 = (10 - 
)/2 = 5 - 
> 0
y2 = (10 + )/2 = 5 + > 0
y1 = 5 -
x1 =
x2 =
y2 = 5 +
x3 =
x4 =
2) х² = у
у² + 4у - 21 = 0
D = 16 + 84 = 100 = 10²
y1 = (-4-10)/2 = -7 < 0 - не интересно
y2 = (-4+10)/2 = 3 > 0
x1,2 = ±
