Đáp án:
\(y=-4\)
Giải thích các bước giải:
\(\eqalign{
& y = x - \left| x \right| \cr
& Cho\,\,x = - 2 \Rightarrow y = - 2 - \left| { - 2} \right| = - 2 - 2 = - 4 \cr
& \Rightarrow A\left( { - 2; - 4} \right) \cr
& Cho\,\,x = 1 \Rightarrow y = 1 - \left| 1 \right| = 1 - 1 = 0 \cr
& \Rightarrow B\left( {1;0} \right) \cr
& Goi\,\,pt\,\,duong\,\,thang\,\,AB\,\,la\,\,y = ax + b\,\,\left( d \right) \cr
& A \in d \Rightarrow - 4 = - 2a + b \cr
& B \in d \Rightarrow 0 = a \cr
& \Rightarrow \left\{ \matrix{
- 2a + b = - 4 \hfill \cr
a = 0 \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{
a = 0 \hfill \cr
b = - 4 \hfill \cr} \right. \Rightarrow AB:\,\,y = - 4 \cr} \)
