5y - x = 4
x² + 3y² = 4
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x = 5y - 4
x² = 25y² - 40y + 16
25y² - 40y + 16 + 3y² = 4
28y² - 40y + 12 = 0
4( 7y² - 10y + 3 ) = 0
D = 100 - 84 = 16 ;√ 16 = 4
y1 = ( 10 + 4 ) : 14 = 1
y2 = ( 10 - 4 ) : 14 = 6/14 = 3/7
x = 5y - 4
x1 = 5*1 - 4 = 1
x2 = 5*( 3/7 ) - 4 = ( 15/7 ) - ( 28/7 ) = - 13/7 = - 1 6/7
Ответ ( 1 ; 1 ) ; ( - 1 6/7 ; 3/7 )