{ x + y = 10
{ √x + √y = 4
{ x = 10 - y
{ √(10 - y) + √y = 4
(√(10 - y) + √y)² = 4²
10 - y + 2√(10y - y²) + y = 16
2√(10y - y²) = 6
√(10y - y²) = 3
(√(10y - y²))² = 3²
10y - y² - 9 =0
y² - 10y + 9 = 0
D = 100 - 36 = 64
y1 = (10 + 8) / 2 = 9
y2 = 1
Если y = 9, то х = 10 - 9 = 1
Если у = 1, то х = 9