Question

bài 39:giải các phương trình sau

a)\(\sqrt{2}.x-\sqrt{98}=0\) b)\(\sqrt{2a}=\sqrt{8}\)

c)\(\sqrt{5}.X^2=\sqrt{20}\) d)\(2x^2-\sqrt{100}=0\)

Answer 1

a, \(\sqrt{2}.x-\sqrt{98}=0\)

\(\Leftrightarrow\sqrt{2}.x=\sqrt{98}\)

\(\Leftrightarrow x=\sqrt{48}\)

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b, \(\sqrt{2a}=\sqrt{8}\)

\(\Leftrightarrow\sqrt{2}.\sqrt{a}=\sqrt{8}\)

\(\Leftrightarrow\sqrt{a}=\sqrt{4}\)

\(\Rightarrow a=4\)

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c, \(\sqrt{5}.x^2=\sqrt{20}\)

\(\Leftrightarrow x^2=\sqrt{4}=2\)

\(\Leftrightarrow x=\sqrt{2}\)

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d, \(2x^2-\sqrt{100}=0\)

\(\Leftrightarrow2x^2=\sqrt{100}\)

\(\Leftrightarrow\sqrt{4}.x^2=\sqrt{100}\)

\(\Leftrightarrow x^2=\sqrt{25}\)

\(\Leftrightarrow x^2=5\)

\(\Leftrightarrow x=\sqrt{5}\)

Vậy...