Question

Giải phương trình:

1. \(2\sqrt{9x-27}-\frac{1}{5}\sqrt{25x-75}-\frac{1}{7}\sqrt{49x-147}=20\)

2.\(\frac{3}{2}\sqrt{5x}+\sqrt{5x}-7=\frac{1}{2}\sqrt{5x}\)

Answer 1

1. ĐKXĐ: \(x\ge3\)

\(2\sqrt{9x-27}-\frac{1}{5}\sqrt{25x-75}-\frac{1}{7}\sqrt{49x-147}=20\)

⇔ \(6\sqrt{x-3}-\sqrt{x-3}-\sqrt{x-3}=20\)

⇔ \(4\sqrt{x-3}=20\)

⇔ \(\sqrt{x-3}=5\)

⇔ \(x-3=25\)

⇔ \(x=28\left(TMĐKXĐ\right)\)

Vậy....

Answer 2

2. ĐKXĐ: \(x\ge0\)

\(\frac{3}{2}\sqrt{5x}+\sqrt{5x}-7=\frac{1}{2}\sqrt{5x}\)

⇔ \(\frac{3}{2}\sqrt{5x}+\sqrt{5x}-\frac{1}{2}\sqrt{5x}=7\)

⇔ \(2\sqrt{5x}=7\)

⇔ \(\sqrt{5x}=\frac{7}{2}\)

⇔ \(5x=\frac{49}{4}\)

⇔ \(x=\frac{49}{20}\left(TMĐKXĐ\right)\)

Vậy...