Toán Lớp 8: Rút gọn biểu thức:
(x-3)(x^2+3x+9)-(x^2-1)(x+27)
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Toán Lớp 8: Rút gọn biểu thức:
(x-3)(x^2+3x+9)-(x^2-1)(x+27)
Comments ( 2 )
$=(x-3)(x^2+3x+3^2)-(x^3+27x^2-x-27)$
$=(x^3-3^3)-(x^3+27x^2-x-27)$
$=x^3-27-x^3-27x^2+x+27$
$=-27x^2+x$