3 √2x+1/7 √98x- √72x+4=0 tìm x

1 câu trả lời

$\text{3$\sqrt{2x}+$$\dfrac{1}{7}$$\sqrt{98x}-$$\sqrt{72x}+4=0$}$

⇔ $\text{ 3$\sqrt{2x}+$$\dfrac{1}{7}.7\sqrt{2x}-$6$\sqrt{2x}$+4=0}$

⇔$\text{3$\sqrt{2x}+\sqrt{2x}-6\sqrt{2x}+4=0$}$

⇔$\text{4-$2\sqrt{2x}$=0}$

⇔$\text{2(2-$\sqrt{2x})$=0}$

⇔$\text{2-$\sqrt{2x}$=0}$

⇔$\text{$\sqrt{2x}$=2}$

⇔$\text{$(\sqrt{2x}$)²=4}$

⇔$\text{2x=4}$

⇔$\text{x=2}$

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