Question

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

Answer 1

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

\(< =>2\sqrt{9\left(x-3\right)}-\frac{1}{5}\sqrt{25\left(x-3\right)}-\frac{1}{7}\sqrt{49\left(x-3\right)}=20\)

\(< =>2\cdot3\sqrt{\left(x-3\right)}-\frac{1}{5}.5\sqrt{\left(x-3\right)}-\frac{1}{7}.7\sqrt{\left(x-3\right)}=20\) \(đk:x\ge0\)

\(< =>6\sqrt{\left(x-3\right)}-\sqrt{\left(x-3\right)}-\sqrt{\left(x-3\right)}=20\)

\(< =>\sqrt{\left(x-3\right)}\left(6-1-1\right)=20\)

\(< =>4\sqrt{\left(x-3\right)}=20\)

\(< =>\sqrt{\left(x-3\right)}=5\)

\(< =>x-3=25\)

\(< =>x=28\left(tm\right)\)