√ ( x + y ) = a ==> x + y = a²
√ ( x² + xy ) = b ==> x² + xy = b²
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a + b = 3
a² + b² = 5
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b = 3 - a
a² + 9 - 6a + a² = 5
2a² - 6a + 4 = 0
D = 36 - 32 = 4 = 2²
a1 = ( 6 + 2 ) : 4 = 2
a2 = ( 6 - 2 ) : 4 = 1
b1 = 3 - 2 = 1
b2 = 3 - 1 = 2
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√ ( x + y ) = 2
√ ( x² + xy ) = 1
x + y = 4 ==> y = 4 - x
x² + xy = 1
x² + x( 4 - x ) = 1
x² + 4x - x² = 1
x = 0,25
y = 4 - 0,25 = 3,75
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√ ( x + y ) = 1
√ ( x² + xy ) = 2
x + y = 1 ==> y = 1 - x
x² + x( 1 - x ) = 4
x² + x - x² = 4
x = 4
y = 1 - 4 = - 3
Ответ ( 4 ; - 3 ) ; ( 0,25 ; 3,75 )