Question

Giúp mik gấp với các bạn!! Cảm ơn ạ!!

Answer 1

a) ĐKXĐ: \(x\ge-\dfrac{1}{3}\)

\(\sqrt{3x+1}=7\\ \Leftrightarrow3x+1=49\\ \Leftrightarrow x=16\)

b) \(3\sqrt{9x-27}-\dfrac{1}{5}\sqrt{25x-75}-\dfrac{1}{7}\sqrt{49x-147}=21\\ \Leftrightarrow9\sqrt{x-3}-\sqrt{x-3}-\sqrt{x-3}=21\\ \Leftrightarrow7\sqrt{x-3}=21\\ \Leftrightarrow\sqrt{x-3}=3\\ \Leftrightarrow x-3=9\\ \Leftrightarrow x=12\)