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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: cho biểu thức M= x^2-x+5. tìm GTNN

Toán Lớp 8: cho biểu thức M= x^2-x+5. tìm GTNN

Comments ( 1 )

  1. $\text{M = x² – x + 5}$
    $\text{= x² – 2.x.}$ $\dfrac{1}{2}$ + $\dfrac{1}{4}$ + $\dfrac{19}{4}$ 
    $\text{= (x – }$ $\dfrac{1}{2}$)² + $\dfrac{19}{4}$ 
    $\text{mà}$ $\text{ (x – }$ $\dfrac{1}{2}$)² ≥ 0 ∀ x
    ⇒ M ≥ $\dfrac{19}{4}$ 

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222-9+11+12:2*14+14 = ? ( )