Toán Bài tập đại số 9

V

vansang02121998

$x^3+y^3=2x^2y^2$

$\Leftrightarrow \dfrac{x^3+y^3}{x^2y^2}=2$

$\Leftirghtarrow \dfrac{x}{y^2}+\dfrac{y}{x^2}=2$

$\Rightarrow (\dfrac{x}{y^2}+\dfrac{y}{x^2})^2=4$

$\Leftrightarrow (\dfrac{x}{y^2}+\dfrac{y}{x^2})^2-\dfrac{4}{xy}=4-\dfrac{4}{xy}$

$\Leftrightarrow (\dfrac{x}{y^2}-\dfrac{y}{x^2})^2=4(1-\dfrac{1}{xy})$

$\Leftrightarrow 1-\dfrac{1}{xy}=\dfrac{(\dfrac{x}{y^2}-\dfrac{y}{x^2})^2}{4}$

$\Leftrightarrow \sqrt{1-\dfrac{1}{xy}}=|\dfrac{\dfrac{x}{y^2}-\dfrac{y}{x^2}}{2}|$
 
G

ginblue

bài này khó thât day m o giai duoc sorry:( nhung minh m biet giai mot so dang max min day :D co bai nao trao doi voi m nhe
 
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