Bai 4: Chopt: x_1 x_2 Gci x^2 - 3 z + 1 = 0 la 2 - Dicamon

Question

Bai 4: Chopt:  x_1 x_2 Gci  x^2 - 3 z + 1 = 0 la 210 ciapt (1). Ko giaupt, tinh gia to carbicithec  A = x_1^3 x_2 + x_2( x_1 + x_2 ) - 5.

Answer

x^2 - 3 x + 1 = 0 .  Δ = ( - 3  )^2 - 1 = 8 > 0 ⇒ pt có 2nghiêm phân biet. Theo he thic Uiet:  { x_1 + x_2 = - b/a = 3 .   x_1· x_2 = c/a = 1  .  .  A = x_1^3· x_2 + x_2·( x_1 +

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