Toán Lớp 9: Tìm MIn B= $x^{2}+3x+4$
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Toán Lớp 9: Tìm MIn B= $x^{2}+3x+4$
Nhanh nha
Comments ( 2 )
=$x^{2}$ +$2.\dfrac{2}{3}x+$ $\dfrac{9}{4}$ $+4-\dfrac{9}{4}$
=$(x-\dfrac{3}{2})^{2}+\dfrac{7}{4}$
Vậy$ Min B= \dfrac{7}{4}$
Dấu “=” xảy ra
<=> $(x-\dfrac{3}{2})^{2}=0$
<=>$x-\dfrac{3}{2}=0$
<=>$x=-\dfrac{3}{2}$
Vậy…..