Toán Lớp 9: ( căn x ) / ( căn x) + 5 = 1 / 2
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Toán Lớp 9: ( căn x ) / ( căn x) + 5 = 1 / 2
Comments ( 2 )
ĐK: x>=0
<=>$\dfrac{\sqrt{x}}{\sqrt{x}+5}-\dfrac{1}{2}=0$
<=>$\dfrac{2\sqrt{x}-(\sqrt{x}+5)}{2(\sqrt{x}+5)}=0$
<=>$\dfrac{2\sqrt{x}-\sqrt{x}-5}{2(\sqrt{x}+5)}=0$
<=>$\dfrac{\sqrt{x}-5}{2(\sqrt{x}+5)}=0$
=>\sqrt{x}-5=0
<=>\sqrt{x}=5
<=>(\sqrt{x})^2=5^2
<=>x=25(N)
Vậy S={25}