Toán Lớp 9: Rút gọn biểu thức:
$A$ = $\frac{4}{\sqrt{x} +2}$ +$\frac{2\sqrt{x}}{x-4}$ :$\frac{\sqrt{x}}{\sqrt{x}-2}$ với x>0, x $\neq$ 4
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Toán Lớp 9: Rút gọn biểu thức:
$A$ = $\frac{4}{\sqrt{x} +2}$ +$\frac{2\sqrt{x}}{x-4}$ :$\frac{\sqrt{x}}{\sqrt{x}-2}$ với x>0, x $\neq$ 4
Comments ( 2 )
A=4/(sqrtx+2)+(2sqrtx)/(x-4):(sqrtx)/(sqrtx-2)(x>=0;x ne 4)
=4/(sqrtx+2)+(2sqrtx)/(x-4).(sqrtx-2)/(sqrtx)
=4/(sqrtx+2)+2/(sqrtx+2)
=(4+2)/(sqrtx+2)
=6/(sqrtx+2)
Điều kiện : x >0 ; x \ne 4
A = 4/(\sqrt{x}+2) + (2 \sqrt{x})/(x-4) : (\sqrt{x})/(\sqrt{x}-2)
= 4/(\sqrt{x}+2) + (2 \sqrt{x})/(x-4) . (\sqrt{x}-2)/(\sqrt{x})
= 4/(\sqrt{x}+2) + 2/(\sqrt{x}+2)
= 6/(\sqrt{x}+2)