cho hàm số y=f(x)= |3x-2| tìm x biết f(x)=0, f(x)=1, f(x)=1/4, f(x)=2006 18/08/2021 Bởi Adalynn cho hàm số y=f(x)= |3x-2| tìm x biết f(x)=0, f(x)=1, f(x)=1/4, f(x)=2006
Đáp án: $\begin{array}{l} + )f\left( x \right) = 0\\ \Rightarrow \left| {3x – 2} \right| = 0\\ \Rightarrow 3x – 2 = 0\\ \Rightarrow x = \frac{2}{3}\\ + )f\left( x \right) = 1\\ \Rightarrow \left| {3x – 2} \right| = 1\\ \Rightarrow \left[ \begin{array}{l}3x – 2 = 1\\3x – 2 = – 1\end{array} \right.\\ \Rightarrow \left[ \begin{array}{l}x = 1\\x = \frac{1}{3}\end{array} \right.\\ + )f\left( x \right) = \frac{1}{4}\\ \Rightarrow \left| {3x – 2} \right| = \frac{1}{4}\\ \Rightarrow \left[ \begin{array}{l}3x – 2 = \frac{1}{4}\\3x – 2 = – \frac{1}{4}\end{array} \right.\\ \Rightarrow \left[ \begin{array}{l}x = \frac{3}{4}\\x = \frac{7}{{12}}\end{array} \right.\\ + )f\left( x \right) = 2016\\ \Rightarrow \left| {3x – 2} \right| = 2016\\ \Rightarrow \left[ \begin{array}{l}3x – 2 = 2016\\3x – 2 = – 2016\end{array} \right.\\ \Rightarrow \left[ \begin{array}{l}x = \frac{{2018}}{3}\\x = \frac{{ – 2014}}{3}\end{array} \right.\end{array}$ Bình luận
Đáp án:
$\begin{array}{l}
+ )f\left( x \right) = 0\\
\Rightarrow \left| {3x – 2} \right| = 0\\
\Rightarrow 3x – 2 = 0\\
\Rightarrow x = \frac{2}{3}\\
+ )f\left( x \right) = 1\\
\Rightarrow \left| {3x – 2} \right| = 1\\
\Rightarrow \left[ \begin{array}{l}
3x – 2 = 1\\
3x – 2 = – 1
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = 1\\
x = \frac{1}{3}
\end{array} \right.\\
+ )f\left( x \right) = \frac{1}{4}\\
\Rightarrow \left| {3x – 2} \right| = \frac{1}{4}\\
\Rightarrow \left[ \begin{array}{l}
3x – 2 = \frac{1}{4}\\
3x – 2 = – \frac{1}{4}
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = \frac{3}{4}\\
x = \frac{7}{{12}}
\end{array} \right.\\
+ )f\left( x \right) = 2016\\
\Rightarrow \left| {3x – 2} \right| = 2016\\
\Rightarrow \left[ \begin{array}{l}
3x – 2 = 2016\\
3x – 2 = – 2016
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = \frac{{2018}}{3}\\
x = \frac{{ – 2014}}{3}
\end{array} \right.
\end{array}$
.