Toán Lớp 8: x(x^2+1)=10(x^2+1) tìm x lớp 8
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Toán Lớp 8: x(x^2+1)=10(x^2+1) tìm x lớp 8
Comments ( 2 )
$⇔x^3+x-10x^2-10=0$
$⇔x^3-10x^2+x-10=0$
$⇔x^2(x-10)+(x-10)=0$
$⇔(x^2+1)(x-10)=0(1)$
$x^2≥0⇔x^2+1≥1$
$(1)⇒x-10=0$
$x=10$
Vậy S={10}