Răspuns :

Mateiid

a * b = 56

a + b = 15

a = 15 - b

(15 - b) * b = 56

15b - b^2 = 56

b^2 - 15b + 56 = 0

  • ecuatie de gradul al doilea

Δ = (-15)^2 - 4 * 1 * 56

Δ = 225 - 224 = 1

b1 = (15+1)/2 = 16/2 = 8

b2 = (15-1)/2 = 14/2 = 7

cazul 1) b = 8 -> a = 7

cazul 2) b = 7 -> a = 8

Solutie

(a, b) ∈ {(7,8) ; (8,7)}

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