rút gọn các biểu thức sau :
\(A=b^5\sqrt{\dfrac{a^2+6a+9}{b^8}}\)
\(B=\dfrac{x+y+2\sqrt{xy}}{x\sqrt{x}-y\sqrt{y}+x\sqrt{y}-y\sqrt{x}}\)
\(A=b^5\sqrt{\dfrac{a^2+6a+9}{b^8}}\)
\(A=b^5\dfrac{\sqrt{\left(a+3\right)^2}}{\sqrt{b^8}}\)
\(A=b^5\dfrac{|a+3|}{b^4}=b|a+3|\)
\(B=\dfrac{x+y+2\sqrt{xy}}{x\sqrt{x}-y\sqrt{y}+x\sqrt{y}-y\sqrt{x}}\)
\(B=\dfrac{\left(\sqrt{x}+\sqrt{y}\right)^2}{\left(x-y\right)\left(\sqrt{x}+\sqrt{y}\right)}=\dfrac{\sqrt{x}+\sqrt{y}}{x-y}\)
\(B=\dfrac{\sqrt{x}+\sqrt{y}}{\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)}=\dfrac{1}{\sqrt{x}-\sqrt{y}}\)
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