Toán Lớp 8: (x+1)(x-2)-x(x-1)
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Toán Lớp 8: (x+1)(x-2)-x(x-1)
Làm giúp mình với nhé
Comments ( 2 )
(x+1)(x-2)-x(x-1)
= x.x-x.2+1.x-1.2-(x.x-x.1)
= x^2 -2x+x-2-(x^2 -x)
= x^2 -x-2-x^2 +x
= (x^2 -x^2)+(-x+x)-2
= -2
$\left(x+1\right)\left(x-2\right)-x\left(x-1\right)$
$=x^2-x-2-x\left(x-1\right)$
$=x^2-x-2-x^2+x$
$=x^2-x^2-x+x-2$
$=-x+x-2$
$=-2$