Răspuns:
Explicație pas cu pas:
(x + a)(x+ b) = x^2 + (a + b)*x + a*b
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x^2 + 5x + 6
a + b = 5
a*b = 6
a = 2; b = 3
x^2 + 5x + 6 = (x + 2)(x + 3)
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x^2 - 9x + 20
a + b = -9
a*b = 20
a = -4; b = -5
x^2 - 9x + 20 = (x - 4)(x - 5)
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x^2 + 6x - 7
a + b = 6
a*b = -7
a = 7; b = -1
x^2 + 6x - 7 = (x + 7)(x - 1)
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x^2 - 12x + 20
a + b = -12
a*b = 20
a = -10
b = -2
x^2 - 12x + 20 = (x - 10)(x - 2)
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