Toán Lớp 9: Giải phương trình
1)5-3 √x =6√x+7
2)15-8 √x=9-5 √x
3)5-( √x-6)=4(3-2 √x)
4)7-(2 √x+4)=-( √x+4)
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Toán Lớp 9: Giải phương trình
1)5-3 √x =6√x+7
2)15-8 √x=9-5 √x
3)5-( √x-6)=4(3-2 √x)
4)7-(2 √x+4)=-( √x+4)
Comments ( 2 )
1)x \in \emptyset \\
2)x = 4\\
3)x = \dfrac{1}{{49}}\\
4)x = 49
\end{array}\)
1)DK:x \ge 0\\
5 – 3\sqrt x = 6\sqrt x + 7\\
\to 9\sqrt x = – 2\left( {KTM} \right)\\
\to x \in \emptyset \\
2)DK:x \ge 0\\
15 – 8\sqrt x = 9 – 5\sqrt x \\
\to 6 = 3\sqrt x \\
\to \sqrt x = 2\\
\to x = 4\\
3)DK:x \ge 0\\
5 – \left( {\sqrt x – 6} \right) = 4\left( {3 – 2\sqrt x } \right)\\
\to 11 – \sqrt x = 12 – 8\sqrt x \\
\to 7\sqrt x = 1\\
\to \sqrt x = \dfrac{1}{7}\\
\to x = \dfrac{1}{{49}}\\
4)DK:x \ge 0\\
7 – \left( {2\sqrt x + 4} \right) = – \sqrt x – 4\\
\to 3 – 2\sqrt x = – \sqrt x – 4\\
\to \sqrt x = 7\\
\to x = 49
\end{array}\)