Đáp án:
B5:
b) x=1
Giải thích các bước giải:
\(\begin{array}{l}
B5:\\
a)\left| {4 - x} \right|.9 = 36\\
\to \left| {4 - x} \right| = 4\\
\to \left[ \begin{array}{l}
4 - x = 4\\
4 - x = - 4
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 0\\
x = 8
\end{array} \right.\\
b)DK:x > 0\\
\dfrac{{x + \sqrt x + 1}}{{\sqrt x }} = 3\\
\to x + \sqrt x + 1 = 3\sqrt x \\
\to x - 2\sqrt x + 1 = 0\\
\to {\left( {\sqrt x - 1} \right)^2} = 0\\
\to \sqrt x - 1 = 0\\
\to x = 1\\
c)DK:x \ge 5\\
\dfrac{{\sqrt {x - 5} }}{{\sqrt {x - 4} }} = 1\\
\to \sqrt {x - 5} = \sqrt {x - 4} \\
\to x - 5 = x - 4\\
\to - 5 = - 4\left( l \right)\\
\to x \in \emptyset
\end{array}\)
