Решение во вложении........................
(√5 +2)² -4√5 = (√5)² + 2√5 *2 +2² -4√5 = 5+4√5 +4 - 4√5 = 9
5x^4-20x^2=0
5x^2*(x^2-4)=0
5x^2*(x-2)*(x+2)=0
x^2*(x-2)*(x+2)=0
x^2=0 x1=0
x-2=0 x2=2
x+2=0 x3=-2
2xy + x = 5
2xy + y = 6
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у - х = 1
2xy + y = 6
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у = х + 1
2х( х + 1 ) + х + 1 = 6
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у = х + 1
2хˆ2 + 3х - 5 = 0
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у1 = -1,5
х1 = -2,5
у2 = 2
х2 = 1