Toán Lớp 8: Chung minh rằng x2+2x+3)0với mọi x
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Toán Lớp 8: Chung minh rằng x2+2x+3)0với mọi x
Comments ( 2 )
$=x^2+2x+1+2$
$=(x+1)^2+2$
$(x+1)^2≥0∀x$
$⇒(x+1)^2+2≥2∀x$
Vậy $x^2+2x+3≥0$ với $∀x$