toán 8 nhân phân thức

C

chaugiang81


a. $\dfrac{x^2 -4}{2x} . \dfrac{6}{3x-6}$
$=\dfrac{(x-2)(x+2).2}{2x. (x-2)}$
$=\dfrac{x+2}{x}$
b.
$(x^2 -1)(\dfrac{1}{2(x+1)^2})$
$=(x-1)(x+1)\dfrac{1}{2(x+1)^2}$
$=\dfrac{x-1}{2(x+1)}$
 
P

pinkylun

c)$ (6-\dfrac{2x}{x^2}+4x+4 ).( x^3+2x^2)$

$=(10-\dfrac{2}{x}+4x)(x^3+2x^2)$

$=10x^3+20x^2-2x^2-4x+4x^4+8x^3$

$=4x^4+18x^3+18x^2-4x$

d) $(x^2+7x+\dfrac{12}{x^2}+3x) ( \dfrac{x^2}{x^2}-16)$

$=(x^2+10x+\dfrac{12}{x^2})(1-16)$

$=-15x^2-150x-\dfrac{180}{x^2}$
 
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