Giải thích các bước giải:
Em tách hỏi từng câu thôi nhé
\(\begin{array}{l}
1)\,a)\, = 2\sqrt 3 - 3\sqrt 3 + 4\sqrt 3 = 3\sqrt 3 \\
b)\, = \dfrac{{5\sqrt 2 - \sqrt 2 }}{{\sqrt 2 }} = 2\sqrt 2 \\
c)\, = \dfrac{{7\left( {3 + \sqrt 2 } \right) + 7\left( {3 - \sqrt 2 } \right)}}{{\left( {3 - \sqrt 2 } \right)\left( {3 + \sqrt 2 } \right)}} = \dfrac{{42}}{7} = 6\\
2)a) \Leftrightarrow \sqrt {25\left( {x - 1} \right)} - \sqrt {16\left( {x - 1} \right)} = 1\,\left( {DK:x \ge 1} \right)\\
\Leftrightarrow 5\sqrt {x - 1} - 4\sqrt {x - 1} = 1\\
\Leftrightarrow \sqrt {x - 1} = 1\\
\Leftrightarrow x - 1 = 1 \Leftrightarrow x = 2\left( {tm} \right)\\
b)\, \Leftrightarrow \left| {2x - 1} \right| = 5\\
\Leftrightarrow \left[ \begin{array}{l}
2x - 1 = 5\\
2x - 1 = - 5
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 3\\
x = - 2
\end{array} \right.\\
Bai\,2)\\
b)\,Xet\,pt\,hoanh\,do\,giao\,diem\\
- \dfrac{1}{2}x = 2x + 5\\
\Leftrightarrow \dfrac{3}{2}x = - 5 \Leftrightarrow x = - \dfrac{{10}}{3} \Rightarrow y = \dfrac{5}{3}\\
\Rightarrow M\left( { - \dfrac{{10}}{3};\dfrac{5}{3}} \right)\,\\
c)\,Vi\,dt\,y = ax + b\,//\left( {{d_2}} \right) \Rightarrow \left\{ \begin{array}{l}
a = 2\\
b \ne 5
\end{array} \right.\\
\Rightarrow y = 2x + b\\
Thay\,x = 1;y = - 1\,vao\,ham\,so\,ta\,co\\
- 1 = 2.1 + b \Leftrightarrow b = - 3\left( {tm} \right)\\
\Rightarrow y = 2x - 3
\end{array}\)
