Răspuns:
Explicație pas cu pas:
d) 2x = y+3
3x+y = 8-y
x-7y = -5
2x = 4y => x = 2y
4y = y+3 => 3y = 3 => y = 1 => x = 2
6+1 = 8-1 , corect
2-7 = -5 , corect
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e) y+3x = x²
y-x = 5 => y = x+5
x+5+3x = x² => x²-4x-5 = 0
x₁,₂ = (4±√(16+20))/2 = (4±6)/2 =>
x₁ = -1 ; x₂ = 5
y₁ = 4 ; y₂ = 10
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f) ∛x = 4-∛y
x+y = 28 => x = 28-y
xy = 27 => y(28-y) = 27
y²-28y+27 = 0 => y₁,₂ = (28±√(784-108)/2
y₁,₂ = (28±26)2 => y₁ = 1 ; y₂ = 27
y₁ = 1 => x₁ = 27
y₂ = 27 => x₂ = 1
